JP3054524B2 - Drive control circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a drive control circuit, and more particularly, to an improvement in a drive control circuit for controlling a motor used in a vacuum cleaner or the like by controlling a phase by a thyristor.

[0002]

2. Description of the Related Art A conventional drive control circuit will be described below with reference to the drawings. As shown in FIG. 5, a drive control circuit according to a conventional example is a circuit including an AC power supply (1), a thyristor (TH1), a bridge circuit (3), and a phase control circuit (4). A circuit for controlling the number of revolutions of a motor (2) used for a vacuum cleaner or the like as a load by controlling the ON / OFF operation of the thyristor (TH1) by a phase control circuit (4) and controlling the phase of the AC voltage. It is.

The operation of the circuit is as follows. First, when an AC voltage is supplied from an AC power supply (1), full-wave rectification is performed by a bridge circuit (3) and a DC voltage including a ripple is applied to a phase control circuit (4). You. At this point, the thyristor (TH
1) is in the OFF state. Then, a DC voltage including a ripple is applied between the points c and d in FIG. 5, so that the capacitor (C1) is charged by the time constant of the resistor (R1) and the capacitor (C1), FIG. 5b
The potential at the point increases.

Next, the potential of the points a and b is compared by the comparator (5). Since the potential at the point a is a potential obtained by dividing the DC voltage including the ripple applied between the points c and d by the bleeder ratio of the variable resistor (R2) and the resistor (R3), the variable resistor (R2) It is constant unless changed. Initially, the potential at the point a is higher than the potential at the point b, the comparator (5) is in the OFF state, and the transistors (TR1, TR2) are in the OFF state.

When the potential at the point b gradually rises and exceeds the potential at the point a, which is the reference potential of the comparator (5), the comparator (5) is turned on and the transistors (TR1, TR1)
2) are both turned on, so that the switching transistor (TR) connected to the emitter of the transistor (12)
3) is turned on in conjunction with it. Then, a collector current flows through the transistor (TR3), and the thyristor (TH3)
1) A diode (D1 or D1) connected to the gate of
Since a current flows through 3) and a trigger current flows through the gate of the thyristor (TH1), the thyristor (TH1) is turned on.

When the thyristor (TH1) is turned on, an AC voltage is supplied to the motor (2), and the motor (12) operates. The operation will be described with reference to the graph of FIG. In FIG. 6, the upper graph is a graph showing the waveform of the AC voltage supplied from the AC power supply (1), and the lower graph is a graph showing the waveform of the voltage applied to the motor.

As shown in FIG. 6, a thyristor (TH1)
Until is turned on, the AC voltage is not supplied to the motor (2) at all. When the thyristor (TH1) is turned on, an AC voltage having the same phase as the AC voltage from the AC power supply (1) is supplied. As a result, the AC voltage is not supplied to the motor (2) during the time until the thyristor (TH1) is turned on in each cycle, and no power is consumed, so that power consumption can be reduced. Also, this thyristor (TH1) is ON
The time until the power is supplied can be adjusted by an external variable resistor (R2) that sets the potential at the point a, so that the power supplied to the motor (2) can be adjusted, and the rotation speed of the motor (2) can be adjusted. can do.

How the time until the thyristor (TH1) is turned on can be controlled by the variable resistor (R2) will be described below with reference to FIG. The potential at point a in the circuit of FIG. 5 is the reference potential of the comparator (5) and can be set by the bleeder ratio between the variable resistor (R2) and the resistor (R3). The potential at point a can be adjusted by changing the variable resistor (R2) in a range from around 0 V to around the potential at point c, as shown in FIG.

The potential at point b in the circuit of FIG.
1) Since the trigger current rises as shown in FIG. 7 by the time constant set by the resistor (R1), the trigger current is generated earlier when the potential at the point a is lowered, and conversely when the potential is higher, the trigger current is delayed. Since the time until the trigger current is generated can be adjusted in this manner, the time until the thyristor (TH1) is turned on by the variable resistor (R2) can be controlled.

In the above-described drive control circuit, it is necessary to provide a variable resistor (R2) for adjusting the rotation speed of the motor (2) outside the apparatus (in this case, a vacuum cleaner). At this time, the variable resistor (R2), which is a part of the non-insulated electric circuit with respect to the AC power supply (1), is located outside the apparatus, and there is a risk of electric shock if the human body accidentally touches the apparatus. There is a problem that there is.

Therefore, as shown in FIG. 8, high-resistance resistors (r1, r2) are connected in series to a variable resistor (R2),
There has been proposed a circuit that raises the impedance between the AC power supply (1) and the variable resistor (R2) to prevent electric shock.

[0012]

However, according to the drive control circuit of FIG. 8 in which the above-described measures for preventing electric shock are taken,
High resistance (r1, r2) for electric shock prevention is variable resistance (R2)
As shown in the graph of FIG. 9, the range in which the potential of the point a can be changed is narrower than that of the circuit of FIG. 5 where no electric shock is prevented.

Therefore, the range in which the phase can be controlled becomes very narrow as shown in FIG. 9, and the phase cannot be delayed. In order to solve this, a circuit has been proposed in which the resistance value of the resistor (R1) relating to the time constant of the circuit in FIG. 8 is increased to increase the time constant, thereby expanding the phase control range. According to this circuit, since the time constant increases, the potential at the point b in FIG. 8 changes as shown in FIG. 9, and the phase control range becomes slightly wider and the phase can be delayed. The phase cannot be advanced, and in any case, the range of the phase control is narrowed, and the range of adjusting the rotation speed of the motor (2) is narrowed.

[0014]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned conventional disadvantages. As shown in FIG. 1, an AC voltage from an AC power supply (11) is supplied / not supplied to a load (12). Thyristor (TH11) as a switching element
A bridge circuit (13) for rectifying the AC voltage and supplying the rectified AC voltage to a phase control circuit (14); and a thyristor (TH)
11) The phase control circuit (1) for controlling the switching operation
4), wherein the phase control circuit (14) comprises: an electric shock prevention resistor (r), a variable resistor (R12), and a potential setting resistor (R13) connected in series; Time constant setting resistor (R11), time constant setting capacitor (C1
1) and a second time constant setting element (16) connected in series
ON / OFF corresponding to a second potential (Vb) which is a potential at a connection point with the time constant setting capacitor (C11).
An operating voltage sensitive element (ZD1) is connected in parallel to the time constant setting capacitor (C11), and a first potential which is a potential at a connection point between the variable resistor (R12) and the potential setting resistor (R13). A comparator (15) for controlling the operation of the switching element (TR13) based on the result of comparison between the potential (Va) of the switching element and the second potential (Vb).
And a switching transistor (TR13) for controlling the ON / OFF operation of the thyristor (TH11), thereby providing a drive control circuit capable of expanding the range in which phase control is possible while preventing electric shock. Things.

[0015]

According to the drive control circuit of the present invention, as shown in FIG. 1, a first time constant setting resistor (R11) connected in series and a time constant setting in a phase control circuit (14). Capacitor (C11) and first time constant setting resistor (R11)
A second time constant setting element (16) is connected to a connection point between the second time constant setting element (16) and the time constant setting capacitor (C11). The second time constant setting element (16) corresponds to a second potential (Vb). ON
/ OFF voltage sensitive element (ZD1) is connected.

For this reason, as shown in FIG. 2, until the second potential (Vb) starts to rise in conjunction with the rise of the AC voltage and exceeds the ON voltage (Vz) of the voltage sensing element (ZD1), The voltage sensitive element (ZD1) is turned off, and the time constant for setting the change of the second potential (Vb) is the first.
The second potential (Vb) rises according to the time constant only depending on the time constant setting resistor (R11) and the time constant setting capacitor (C11).

Thereafter, the second potential (Vb) rises and turns on.
When the voltage (Vz) is exceeded, the voltage sensitive element (ZD1) turns ON
Therefore, the time constant for the change of the second potential (Vb) depends on the first time constant setting resistor (R11), the second time constant setting element (16) and the time constant setting capacitor (C11). However, it becomes apparently larger than the time constant when the voltage sensitive element (ZD1) is turned off.

As a result, the time constant applied to the change of the second potential (Vb) increases at the boundary of the ON voltage (Vz), and the second potential (Vb) increases according to the time constant. Above the voltage (Vz), the rate of change of the second potential (Vb) decreases, the upper limit of the second potential (Vb) decreases, and the range in which it can change narrows as shown in FIG. Therefore, even if the control range of the first potential (Va) is narrowed by adding the electric shock prevention resistance (r) for preventing electric shock, the second electric potential (V
Since the control range of b) is narrowed and substantially included in the control range of the first potential (Va), the range in which the phase can be controlled is widened as shown in the figure. Therefore, as compared with the conventional phase control circuit in which electric shock prevention measures are taken as shown in FIG. 8, it is possible to extend the range in which phase control is possible while preventing electric shock,
The controllability of the load (12) is improved.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a drive control circuit according to an embodiment of the present invention will be described with reference to the drawings. As shown in FIG. 3, the drive control circuit according to the embodiment of the present invention includes an AC power supply (11), a thyristor (TH11), and a bridge circuit (1).
3) ON of a thyristor (TH11) as a switching element, which is a circuit composed of a phase control circuit (14)
A circuit that controls the number of revolutions of a motor (12) that is a load and is used for a vacuum cleaner or the like by controlling the / OFF operation and controlling the phase of the AC voltage.

In the circuit, a bridge circuit (13)
Is a circuit composed of diodes (D11 to D14), which performs full-wave rectification of an AC voltage supplied from an AC power supply (11) and supplies the rectified voltage to a phase control circuit (14). The phase control circuit (14) includes a comparator (15), a switching transistor (TR13), and an external adjusting variable resistor (R1).
2) First and second time constant setting resistors (R11, R1
4) A circuit comprising a time constant setting capacitor (C11) and a Zener diode (ZD1), and a circuit for controlling the switching of the thyristor (TH11).

The comparator (15) is composed of transistors (TR11, TR12), resistors (R15, R16) and a diode (D15), and compares the potential at point a and the potential at point b in FIG. The transistor (TR11, TR12) is turned on when the potential of the transistor exceeds the potential at the point a, whereby the switching transistor (TR13) is turned on.
Is turned on.

The Zener diode (ZD1) is an example of a voltage-sensitive element. The Zener diode (ZD1) is turned on when the potential at the point b in FIG. 3 exceeds the Zener voltage (Vz). To increase. Here, the second time constant setting resistor (R14) is an example of a time constant setting element, and the Zener diode (ZD1)
Is turned on to increase a time constant described later.

The first time-constant setting resistor (R11) is connected in series with the time-constant setting capacitor (C11), and the second time-constant setting resistor (R14) connected in series with the zener diode (ZD1). Constant setting capacitor (C1
1), the time constant is set by these, the potential at point b is changed, and the thyristor (TH1
The time until 1) is turned on is adjusted.

The operation of the drive control circuit according to the embodiment of the present invention will be described below with reference to the drawings. First, when an AC voltage is applied from an AC power supply (11), a full-wave rectified by a bridge circuit (13) including diodes (D11 to D14) and a DC voltage including a ripple is applied to a phase control circuit (14). You. At this point, the thyristor (TH11) is in the OFF state.

Then, a DC voltage including a ripple is applied between the point a and the point d in FIG.
Charging to 1) is started, and FIG.
The potential at point b rises. The change in the potential at point b at this time will be described below with reference to the graph of FIG. First, with the application of the AC voltage, a DC voltage is applied to the point c in FIG. 3, and the potential at the point b set by the voltage drop of the first time constant setting resistor (R11) gradually increases from 0V. However, since the voltage is initially equal to or lower than the Zener voltage (VZ), the Zener diode (ZD1) is turned off.

Then, the time constant for determining the rise of the potential at the point b in FIG. 3 depends on the first time constant setting resistor (R11) and the time constant setting capacitor (C11), as shown in the graph of FIG. Rise as shown. Thereafter, when the potential at the point b rises and exceeds the Zener voltage (VZ), the Zener diode (ZD1) is turned on.

Then, the potential at the point b in FIG. 3 is changed between the first time constant setting resistor (R11) and the second time constant setting resistor (R1).
4), the rise rate of the potential at the point b decreases, and the time constant for setting the rise of the potential at the point b is a first time constant setting resistor (R11) and a second time constant. Time constant setting resistor (R14) and time constant setting capacitor (C1
1), and changes as if the apparent time constant increased.

That is, as shown in FIG. 4, above the Zener voltage (Vz), the time constant for the change in the potential (Vb) at the point b increases, and the second potential (Vb) according to the increased time constant. ) Increases, the rate of increase of the potential (Vb) at point b decreases, and the range in which the potential can change is narrowed as shown in the figure. Therefore, the electric shock prevention resistance (r1, r
Even if the control range of the potential (Va) at the point a becomes narrow due to the addition of 2), the control range of the potential (Vb) at the point b becomes narrow, and the potential (Va) at the point a as shown in FIG. 4) is almost included in the controllable range, and it can be seen that the range in which the phase can be controlled is widened as shown in FIG.

The operation of the circuit shown in FIG. 3 will be described below. Next, the potential of the points a and b in FIG. 3 is compared by the comparator (15). The potential at the point a does not move the variable resistor (R2) because the DC voltage applied between the points a and d in the figure is a potential divided by the bleeder ratio of the variable resistor (R12) and the resistor (R3). As long as it is constant. Initially, the potential at point a is higher than the potential at point b, and the comparator (1
5) is turned off and the transistors (TR11, T
R12) holds the OFF state.

When the potential at the point b gradually rises and finally exceeds the potential at the point a, the comparator (15) is turned on,
That is, since the transistors (TR11, TR12) are turned on, the switching transistor (TR13) connected to the emitter of the transistor (TR12) is turned on. Then, a collector current flows through the transistor (TR13), a current flows through the diode (D11 or D13) connected to the gate of the thyristor (TH11), and a trigger current flows through the gate of the thyristor (TH11). Is turned on and the motor (1
The AC voltage is applied to 2), and the motor (12) operates. The operation will be described with reference to the graph of FIG.

As shown in FIG. 6, a thyristor (TH1
Until 1) is turned ON, no AC voltage is supplied to the motor (12), and the AC voltage is supplied from the AC power supply (11) by turning on the thyristor (TH11). The time until the thyristor (TH11) is turned on is determined by an external variable resistor (R1) that sets the potential at point a.
2), the motor (1)
The power supplied to 1) can be adjusted, and the rotation speed of the motor (11) can be adjusted. Comparator (15) is ON
While the thyristor (TH11) is ON, the time constant setting capacitor (C11) is connected to the emitter-base of TR11, the collector-emitter of TR12, the resistor connected to the base of the transistor (TR13) and the base of the transistor (TR13). Discharged through the emitter,
Discharged below the potential at point a to prepare for the next charge.

As described above, according to the drive control circuit according to the embodiment of the present invention, as shown in FIG. 3, the first time constant setting serially connected in the phase control circuit (14) is performed. A resistor (R11), a time constant setting capacitor (C11),
A second time constant setting resistor (R14) is connected to a point b which is a connection point between the first time constant setting resistor (R11) and the time constant setting capacitor (C11). R14), ON / O corresponding to the potential (Vb) at point b
A Zener diode (ZD1) that performs FF operation is connected.

For this reason, as shown in FIG. 4, the time constant for setting the change of the potential (Vb) at the point b increases at the boundary of the Zener voltage (Vz), and the time constant at the point b according to the increased time constant increases. Since the potential (Vb) increases, the rate of change of the potential (Vb) at the point b decreases above the Zener voltage (Vz), the upper limit thereof decreases, and the range in which the potential can change is narrowed. Therefore, even if the control range of the potential (Va) at the point a is narrowed by adding the electric shock prevention resistors (r11, r12) for electric shock prevention, b
Since the control range of the potential (Vb) at the point is narrowed and substantially included in the control range of the potential (Va) at the point a, the range in which the phase can be controlled is widened as shown in FIG.

Therefore, as compared with the conventional phase control circuit in which electric shock prevention measures are taken as shown in FIG. 8, the range in which phase control can be performed while preventing electric shock can be expanded, and the rotation speed of the motor can be adjusted. The possible range will also be expandable. In addition,
In the present embodiment, a Zener diode is used as an example of the potential sensitive element, but the present invention is not limited to this.
For example, a similar effect can be obtained with a plurality of diodes connected in series or a bipolar transistor.

Although a resistor is used as the second time constant setting element, the present invention is not limited to this, and a similar effect can be obtained with a capacitor or the like. In addition, although a motor for a vacuum cleaner is used as an example of the load (12), the present invention is not limited to this. For example, a motor used for a juicer, a mixer, a lathe, or a light bulb for a desk lamp may be used. A similar effect is achieved.

[0036]

According to the drive control circuit according to the present invention, the first time constant setting resistor (R11) and the time constant setting capacitor (C1) connected in series in the phase control circuit (14).
1), a second time constant setting element (16) is connected to a connection point between the first time constant setting resistor (R11) and the time constant setting capacitor (C11), and the second time constant setting element ( 1
6), a voltage sensitive element (ZD1) that performs ON / OFF operation corresponding to the second potential (Vb) is connected.

Therefore, even if the control range of the first potential (Va) is narrowed by adding an electric shock prevention resistor (r) for preventing electric shock, the control range of the second potential (Vb) is reduced. Since it is narrowed and substantially included in the control range of the first potential (Va), the range in which the phase can be controlled is widened as shown in the figure. Therefore, as compared with the conventional phase control circuit in which electric shock prevention measures are taken, the range in which phase control can be performed while electric shock is prevented can be expanded, and controllability of the load (12) is improved.

[Brief description of the drawings]

FIG. 1 is a principle diagram of a drive control circuit according to the present invention.

FIG. 2 is a graph illustrating the operation and effect of the drive control circuit according to the present invention.

FIG. 3 is a circuit diagram of a drive control circuit according to an embodiment of the present invention.

FIG. 4 is a graph illustrating the operation and effect of the drive control circuit according to the embodiment of the present invention.

FIG. 5 is a circuit diagram of a first drive control circuit according to a conventional example.

FIG. 6 is a graph illustrating a driving method based on phase control.

FIG. 7 is a graph illustrating an operation of a first drive control circuit according to a conventional example.

FIG. 8 is a circuit diagram of a second drive control circuit according to a conventional example.

FIG. 9 is a graph illustrating a problem of a driving circuit according to a conventional example.

[Explanation of symbols]

 (11) AC power supply (12) Motor [load] (13) Bridge circuit (14) Phase control circuit (15) Comparator (16) Second time constant setting element (R11) First time constant setting resistor (R12) Variable resistor (R13) Potential setting resistor (R14) Second time constant setting resistor (C11) Time constant setting capacitor (r11, r12) Electric shock prevention resistor (ZD1) Zener diode [potential sensitive element] (TH11) Thyristor (TH13) Switching element

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G05F 1/455

Claims (2)

(57) [Claims] A thyristor (TH11), which is a switching element for supplying / non-supplying an AC voltage from an AC power supply (11) to a load (12), and rectifying the AC voltage and supplying the rectified AC voltage to a phase control circuit (14). And a phase control circuit (14) for controlling a switching operation of the thyristor (TH11). The phase control circuit (14) is connected in series with an electric shock prevention resistor (r). , Variable resistor (R12), potential setting resistor (R
13) a first time constant setting resistor (R11) and a time constant setting capacitor (C11) connected in series; a second time constant setting element (16) connected in series; and the time constant setting capacitor A voltage sensitive element (ZD1) that performs ON / OFF operation corresponding to a second potential (Vb) that is a potential at a connection point with (C11), is connected in parallel to the time constant setting capacitor (C11); The variable resistor (R12) and the potential setting resistor (R1
A comparator (15) for controlling the operation of the switching element (TR13) based on a comparison result between the first potential (Va) which is the potential at the connection point with the third potential (Va) and the second potential (Vb). And a switching transistor (TR13) for controlling ON / OFF operation of the thyristor (TH11). 2. A thyristor (TH11), which is a switching element for supplying / non-supplying an AC voltage from an AC power supply (11) to a load (12), and rectifying the AC voltage and supplying the rectified AC voltage to a phase control circuit (14). And a phase control circuit (14) for controlling a switching operation of the thyristor (TH11). The phase control circuit (14) is connected in series with an electric shock prevention resistor (r). , Variable resistor (R12), potential setting resistor (R
13) a first time constant setting resistor (R11) and a time constant setting capacitor (C11) connected in series; a second time constant setting element (16) connected in series; and the time constant setting capacitor A voltage sensitive element (ZD1) that performs ON / OFF operation corresponding to a second potential (Vb) that is a potential at a connection point with (C11), is connected in parallel to the time constant setting capacitor (C11); The variable resistor (R12) and the potential setting resistor (R1
A comparator (15) for controlling the operation of the switching element (TR13) based on a comparison result between the first potential (Va) which is the potential at the connection point with the third potential (Va) and the second potential (Vb). And a switching transistor (TR13) for controlling ON / OFF operation of the thyristor (TH11), and the voltage sensitive element (ZD1) comprises a Zener diode.