JPH06284770A - Method and device for speed control of dc motor and rotating brush device using above described device - Google Patents

Abstract

PURPOSE:To omit a tacho-generator by making electric power flow into a DC motor through a reactance when a switch is ON, taking the reverse electromotive force from the reactance out of a resistor, which is not placed in a main circuit, when the switch is OFF, feeding back the reverse electromotive force, and controlling the opening and closing of the switch. CONSTITUTION:An ON/OFF switch 6, a reactance 7 and a DC motor 8 are connected in series with respect to a battery 5. A capacitor 11 is connected between a first branching point 9 between the battery 5 and the DC motor 8 and a second branching point 10 between the reactance 7 and the DC motor 8. A resistor 4 and a diode 15 are connected in the series state between a third branching point 12 between the first branching point 9 and the battery 5 and a fourth branching point 13 between the switch 6 and the reactance 7. At this time, the output, which is taken out of both ends of the resistor 14, is fed back, and the opening and closing time of the ON/OFF switch 6 and the output torque of the DC motor 8 are controlled.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a DC motor speed control method, a DC motor speed control device, and a rotary brush device using the same. In addition, the rotating brush device is a brush type floor cleaning used for cleaning floors, stairs, etc. that rotate brushes, sponge brushes, brushes sponged with abrasive particles, felt brushes, cloth brushes and other brushes. Machines, floor polishers, stair cleaners, etc.

[0002]

2. Description of the Related Art Generally, speed control of a DC motor is performed by voltage control that changes a power supply voltage.
Also, as a recent technique of this voltage control, it is known to reduce defects when the voltage is controlled by using a switching circuit.

Speed control of a DC motor using this switching circuit is as shown in FIG. 4, for example. That is, the power from the battery 1 is supplied to the switch 2
The electric power supplied to the DC motor 3 is controlled by changing the opening and closing time of the DC voltage. As shown in FIG. The power is 50%, and in the case of the B waveform, the ON / OFF time is 90% and the power applied to the DC motor 3 is 90%.

In the case of controlling the rotation speed of the DC motor by changing the electric power in this way, the output from the DC motor 3 becomes small when the supply power is made small, and the rotation becomes slow when a large load is applied. For this reason, rotation must be guaranteed. Generally, a tachogenerator is attached to the rotary shaft of a motor and its output is fed back to guarantee the rotation.

The speed control device for a DC motor that guarantees rotation by using the tachogenerator described above has a drawback in that the cost is high because the tachogenerator is required.

In addition to the above-mentioned conventional example, a circuit as shown in FIG. 6 is also known. That is, the resistor 14, the ON / OFF switch 6, the reactance 7 and the DC motor 8 are connected in series to the battery 5, and the first branch point between the battery 5 and the DC motor 8 and the reactance 7 / DC motor 8 are connected. A capacitor 11 between the second branch point 10 and
And a diode 15 is connected between the third branch point 12 between the first branch point 9 and the battery 5 and the fourth branch point 13 between the ON / OFF switch 6 and the reactance, and both ends of the resistor 14 are connected. The output taken out is fed back to control the output torque of the DC motor 8.

In the conventional example shown in FIG. 6, the electric power of the battery 5 flows through the DC motor 8, the ON / OFF switch 6 and the resistor 14 only while the ON / OFF switch 6 is closed. Since the flowing current is the load current of the DC motor 8, the voltage V generated across the resistor 14 increases correspondingly when the load of the DC motor 8 is large. By taking out this voltage V and feeding it back, the opening / closing time of the switch, that is, the output torque of the DC motor 8 can be controlled. However, this circuit is disadvantageous especially when the motor is driven by a battery, because the resistor 14 is included in the main current circuit, so that the power loss of the resistor 14 becomes large.

[0008]

DISCLOSURE OF THE INVENTION The present invention uses a device for eliminating the need for a tachogenerator and a device for reducing power loss due to a resistor. It is an object of the present invention to provide a rotating brush device having the above structure.

[0009]

In order to achieve the above object, a method of controlling the speed of a direct current motor according to the present invention uses a power supplied from a battery to supply power to the direct current motor by changing the open / close time of a switch. In the method of controlling the speed of the DC motor by controlling, the electric power from the battery is sent to the DC motor through the reactance when the switch is closed, and the counter electromotive force from the reactance is supplied when the switch is opened. It is made to flow to a resistor that is not in the main circuit, and the output taken out from both ends of this resistor is fed back to control the open / close time of the switch.

Similarly, a DC motor speed control device and a rotary brush device using the same device include a switch, a reactance and a DC motor connected in series to a battery, a first branch point between the battery and the DC motor, and a reactance. A capacitor connected between the second branch point of the DC motor and the third branch between the first branch point and the battery
A resistor and a diode connected in series between the branch point and the fourth branch point between the switch reactance, and a feedback circuit for controlling the open / close time of the switch by feeding back the outputs taken from both ends of the resistor. With and.

[0011]

1 and 2 are circuit diagrams showing an embodiment of the present invention. That is, ON / OFF for the battery 5
The switch 6, the reactance 7 and the DC motor 8 are connected in series, and the first branch point between the battery 5 and the DC motor 8 and the second branch point 1 between the reactance 7 and the DC motor 8 are connected.
Connect a capacitor 11 between 0 and the first branch point 9
A resistor 14 and a diode 15 are connected in series between the third branch point 12 between the battery 5 and the fourth branch point 13 between the ON / OFF switch 6 and the reactance, and the resistor 14 and the diode 15 are taken out from both ends of the resistor 14. Feed back the output
Open / close time of N / OFF switch 6 and DC motor 8
The output torque of is controlled. A semiconductor switch such as a switching transistor or a switching diode is used as the ON / OFF switch 6.

[0012]

In the above embodiment, when the ON / OFF switch 6 is turned on, the current from the battery 5 flows through the DC motor 8, the reactance 7, and the ON / OFF switch 6 as shown in FIG. In this case, the resistor 14 does not flow and does not output (feedback). Also, the same O
When the N / OFF switch 6 is turned off, the main current does not flow to the ON / OFF switch 6 as shown in FIG. However, at this time, the reactance 7 has electric power flowing when the ON / OFF switch 6 is turned on. This power is
As shown in FIG. 5, a counter electromotive force is generated and flows from the reactance 7 through the diode 15, the resistor 14, the capacitor 11 and the DC motor 8. The current at this time is the DC motor 8
Changes depending on the current flowing through the resistor 14, and the output taken from both ends of the resistor 14 has a magnitude according to the torque of the DC motor 8. By feeding this output back to the ON / OFF switch 6, the load fluctuation of the DC motor is caused. You will be able to control.

[0013]

According to the present invention, since the current flowing in the circuit is fed back as described above, the tachogenerator is not necessary, and the resistor 14 is not included in the main circuit, so that the power loss can be extremely reduced. It can be achieved and has an excellent effect of completely achieving the intended purpose.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing an embodiment of the present invention.

FIG. 2 is a circuit diagram showing how a current flows when the switch is turned on.

FIG. 3 is a circuit diagram showing how a current flows when the switch is turned off.

FIG. 4 is a circuit diagram showing a conventional example.

FIG. 5 is a waveform diagram of the same.

FIG. 6 is a circuit diagram showing another conventional example.

[Explanation of symbols]

 1 Battery 2 Switch 3 DC Motor 5 Battery 6 Switch 7 Reactance 8 DC Motor 9 1st Branch Point 10 2nd Branch Point 11 Capacitor 12 3rd Branch Point 13 4th Branch Point 14 Resistor 15 Diode

Claims (3)

[Claims] 1. A method for controlling the speed of a DC motor by controlling the power supplied from the battery to the DC motor by changing the opening / closing time of the switch, wherein the battery is used when the switch is closed. Power from the reactance to the DC motor via the reactance, the counter electromotive force from the reactance to the resistor not in the main circuit when the switch is open, and the output from both ends of this resistor is fed back. The method of controlling the speed of a DC motor is characterized by controlling the opening / closing time of the switch. 2. A switch, a reactance and a DC motor connected in series to the battery, and a capacitor connected between a first branch point between the battery and the DC motor and a second branch point between the reactance and the DC motor. , A resistor and a diode connected in series between the third branch point between the first branch point and the battery and the fourth branch point between the switch reactance and the output extracted from both ends of the resistor are fed back. A DC motor speed control device characterized by having a feedback circuit for controlling the opening / closing time of the switch. 3. A rotary brush device driven by a DC motor, comprising the speed control device for the DC motor according to claim 2.