JP2516669Y2 - Rotation control circuit for brushless DC motor for fan - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to a rotation control circuit for a brushless DC motor for a fan.

[Prior Art] Conventionally, as a rotation control circuit of a brushless DC motor, for example, there is one disclosed in Japanese Patent Laid-Open No. 60-60635. In this rotation control circuit, as shown in FIG. 11, a rectifier circuit that rectifies the current from the power supply,
A motor drive circuit for rotating the motor, a PNP transistor interposed between the rectifier circuit and the drive circuit, and a PNP transistor
It has a phase locked loop (PLL) circuit connected to the base of the NP transistor. The PLL circuit supplies the signal of the set pulse width to the base of the PNP transistor, and while this signal is supplied to the base, the PNP transistor is in the ON state and the drive current is supplied to the motor through the drive circuit. . When the pulse width of the signal supplied from the PLL circuit to the base of the PNP transistor is relatively large (or small), the period in which the PNP transistor is turned on is relatively long (or short), and therefore the current supplied to the drive circuit is The number increases (or decreases), and the rotation speed of the fan increases (or decreases).

[Problems to be Solved by the Invention] However, the known control circuit has the following problems to be solved. That is, since the transistor used is a PNP transistor, the price of the transistor itself is high, and this causes a drawback that the control circuit is expensive. Also, the pulse width of the signal sent to the base of the PNP transistor changes depending on the PLL circuit (which consists of a phase comparator, triangular wave generator, comparator, etc.), so a dedicated circuit for changing the pulse width is required. However, due to this, there is a drawback that the control circuit itself becomes complicated and expensive.

The present invention solves the above-mentioned drawbacks and provides a rotation control circuit for a brushless DC motor for a fan, which has a relatively simple structure and is inexpensive.

[Means for Solving the Problems] According to the present invention, a plurality of windings for rotationally driving a rotor, a plurality of first transistors for switching a current supplied to the plurality of windings, and the plurality of windings are provided. The NPN transistor connected to the low potential side of the winding and the built-in device equipped with a fan generate pulse signals at various intervals to generate NP.
The NPN transistor is provided with a microprocessor, and the NPN transistor switches the low potential side based on the pulse signal, and thus the current flowing through the plurality of windings is duty controlled by the action of the plurality of first transistors and the NPN transistor. To be done.

[Operation] In the control circuit of the present invention, an NPN transistor is used as a transistor, and this NPN transistor is arranged on the low potential side of the control circuit. Therefore, the control circuit can be easily designed and an inexpensive control circuit can be provided. In addition, the pulse width of the signal supplied to the base of the NPN transistor is set by the signal from the microprocessor incorporated in the device equipped with the fan, so a dedicated circuit is not required and the circuit configuration can be simplified. And it can be provided as an inexpensive one.

[Embodiment] An embodiment of a rotation control circuit according to the present invention will be described below with reference to the accompanying drawings.

In FIG. 1, reference numeral 1 is a rotation control circuit for a fan brushless DC motor. The control circuit includes a rotor position detection drive mechanism including two Hall ICs 3 and a microprocessor 2 for generating a pulse waveform. Is attached externally.

Specifically, from the rotor magnet (not shown) to the Hall IC3,
When a magnetic field is applied to 3, the Hall ICs 3 detect the position and strength of the magnetic pole of the rotor magnet by the Hall effect, and the detection signal is converted into an electric signal to detect the rotor position. Is done. In other words, the input signal
Vi is added and the polarity of the rotor (not shown) is Hall IC.
When detected by 3 and 3, the two windings 5 and 5 are alternately excited to form a magnetic field, and repulsive force and attractive force between the magnets generate a rotational torque of the rotor. The emitter currents E5 and E5 of the two PNP transistors 4 and 4 (constituting the first transistor) are base currents B5 and B5 and collector current C.
This base current B is separated into 5 and C5 respectively.
5, B5 is a ground wire 6 through resistors R3, R4 and Hall ICs 3,3
Grounded through. On the other hand, the collector currents C5 and C5 flow into the branch destination 7 extending through the windings 5 and 5.

Further, this branch line 7 is connected to the microprocessor 2 which generates a pulse waveform via the NPN transistor 8 (which constitutes a second transistor), the resistor R5 and the amplifier 9, and the emitter terminal E6 of the NPN transistor 8 is also connected. Grounded through.

In the figure, D is a rectifying diode, RT is a thermistor for circuit compensation, and ZD is a Zener diode that holds the power supply circuit of the Hall IC at a constant voltage.

R1 to R5 are various resistors, and C1 to C3 are various capacitors. These are all incorporated to maintain the stability of the control circuit 1. Therefore, in the rotation control circuit of the DC motor configured as described above, the input signal Vi
When the square-wave pulse signal output from the microprocessor 2 is supplied to the base of the transistor 8 via the amplifier 9, the collector terminal C6 and the emitter terminal E6 of the NPN transistor 8 (grounded) are added. During this period, a switching output is obtained, electric power flows from the branch line 7, and the brushless DC fan is rotated at a desired rotation speed.

FIG. 2 shows pulse waveforms when the microprocessor 2 emits pulse signals at various intervals to control rotation. The vertical axis represents the voltage V and the horizontal axis represents the time T. Further, A indicates a signal in the full speed state, B indicates a signal in the medium speed state, and C indicates a signal in the low speed state.

More specifically, in the full speed state A, the output signal of a constant level
Vo is always output, so the NPN transistor 8 is always on.
The fan motor will rotate at the maximum speed.

When lowering the rotation speed, medium speed state B or low speed state C
What should I do? Assuming that the motor operation time is T1 and the motor stop time is T2, the operation cycle is T1 / (T
1 + T2), and the smaller this value, the slower the rotation speed of the fan motor. For example, when the operating time T1 is relatively long, a signal as shown in the middle of FIG. 2 is supplied from the microprocessor 2, so that the fan motor is rotated in the medium speed state B. When the operation time T1 is relatively short, a signal as shown in the lower part of FIG. 2 is supplied from the microprocessor 2, and therefore the fan motor is rotated in the low speed state C.

When an arbitrary rotation speed is selected in this way, the microprocessor 2 issues a pulse signal corresponding to the rotation speed, and time control, that is, rotation control based on the duty ratio is performed.

Further, in the present invention, without being limited to a constant input,
It is preferable to perform various program controls by a microprocessor incorporated therein in accordance with the use of the OA equipment or control equipment, etc. By doing so, a dedicated one for controlling the rotation of the fan motor can be omitted. .

In the present invention, a Hall element may be used in addition to the Hall IC for detecting the position of the rotor. It can also be applied to other rotation control circuits for brushless DC fans.

[Effect of the device] In the rotation control circuit of the present invention, NPN is used as a transistor.
A transistor is used, and this NPN transistor is arranged on the low potential side of the control circuit. Therefore, in connection with the NPN transistor, the control circuit can be easily designed and an inexpensive control circuit can be provided. Also, NP
The pulse width of the signal supplied to the base of the N-transistor is set by the signal from the microprocessor incorporated in the device equipped with the fan, so no dedicated circuit is required, and the circuit configuration is simple and inexpensive. Can be provided as Further, it is possible to effectively use the microprocessor incorporated in the device equipped with the fan.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing an embodiment of a rotation control circuit of a brushless DC motor for a fan according to the present invention. FIG. 2 is a pulse waveform diagram supplied to the rotation control circuit of FIG. 2 ... Microprocessor 3 ... Hall IC 4 ... First transistor 5 ... Winding 6 ... Ground wire 7 ... Branch wire 8 ... NPN transistor

Claims (1)

(57) [Scope of utility model registration request] 1. A plurality of windings (5, 5) for rotationally driving a rotor, and a plurality of first transistors (4, 4) for switching a current supplied to the plurality of windings (5, 5).
4), an NPN transistor (8) connected to the low potential side of the plurality of windings (5, 5) and a fan-equipped device to generate pulse signals at various intervals. Microprocessor (2) supplying NPN transistor (8)
And the NPN transistor (8) switches the low potential side on the basis of the pulse signal, and thus the current flowing through the plurality of windings (5, 5) is controlled by the plurality of first transistors (4). 4) and the rotation control circuit for a fan brushless DC motor, wherein the duty is controlled by the action of the NPN transistor (8).