JPH04285487A - Driver for single-phase induction motor - Google Patents

Abstract

PURPOSE:To start a single-phase induction motor and to control its rotational direction without using a phase advancing capacitor. CONSTITUTION:Triacs 2, 3 (phase controllable switching means) are connected in series with a main winding 1a and an auxiliary winding 1b of a single-phase induction motor 1 connected in parallel with a single-phase AC power source 4. The phases of the triacs 2, 3 are controlled by a microcomputer (control means) 6.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a drive device for a single-phase induction motor used, for example, in a blower motor for a hot-air fan or a cold-air fan.

0002

[Prior Art] A single-phase induction motor consists of a rotor, a main winding, and an auxiliary winding, and its drive device uses the main winding and auxiliary winding to generate a rotating magnetic field to generate starting torque at the time of starting. ing.

As a drive device for such a single-phase induction motor, a phase advancing capacitor is connected in series with the auxiliary winding, and at the time of starting, the auxiliary winding circuit including the main winding and this phase advancing capacitor is connected to the single phase. It is known that the auxiliary winding circuit is connected in parallel to an AC power source and disconnected from the power source after startup.

In this drive device, at the time of starting, the auxiliary winding circuit in which the phase advancing capacitor is connected in series is connected in parallel to the main winding circuit, so that the current in the main winding circuit and the current in the auxiliary winding circuit are different. A phase difference occurs between the two, which generates a rotating magnetic field.

[0005] Furthermore, as a drive device that can drive a single-phase induction motor in any forward or reverse direction, the one shown in FIG. 4 is known.

In FIG. 4, a single-phase induction motor (1) includes a rotor (14), a main winding (1a), and an auxiliary winding (1a).
b) Consists of. The main winding (1a) and the first triac (2
), the series connection circuit of the auxiliary winding (1b) and the second triac (3) are connected in parallel to the 100V single-phase AC power supply (4), and the main winding (1a) and the first triac (3) are connected in parallel. Midpoint of triac (2) and auxiliary winding (1b)
A phase-advance capacitor (5) is connected between the center point of the second triac (3) and the middle point of the second triac (3). The G terminals of these two triacs (2) and (3) are connected to a control microcomputer (6) (abbreviated as microcomputer). Furthermore, a zero cross detection circuit (7) is provided between the AC power supply (4) and the microcomputer (6).

In this drive device, when the motor (1) is to be rotated in the forward direction, only the first triac (2) is turned on by the microcomputer (6), and when the motor (1) is to be rotated in the reverse direction, only the second triac (3) is turned on. let

When the first triac (2) is turned on, the current flows through the main winding (1a) and the first triac (2).
The route passing through, the auxiliary winding (1b), and the capacitor (5)
and the first triac (2), and a phase difference occurs between the current in the main winding (1a) and the current in the auxiliary winding (1b). 1b) generates a rotating magnetic field in the forward rotation direction.

Conversely, when the second triac (3) is turned on, the current flows through the main winding (1a), the capacitor (5), the second triac (3), and the auxiliary winding (3).
1b) and the second triac (3), a phase difference opposite to the above occurs between the current in the main winding (1a) and the current in the auxiliary winding (1b), and the current in the main winding (1a) ) and the auxiliary winding (1b) generate a rotating magnetic field in the opposite rotation direction.

0010

All of the conventional single-phase induction motor drive devices as described above require a phase advancing capacitor for starting or rotational direction control, which is uneconomical.

[0011] The purpose of the present invention is to solve the above problems,
An object of the present invention is to provide an economical single-phase induction motor drive device that does not require a phase advance capacitor.

0012

[Means for Solving the Problems] A single-phase induction motor drive device according to the present invention has a main winding and an auxiliary winding each connected in series with a main winding and an auxiliary winding of a single-phase induction motor connected in parallel with a single-phase AC power supply. The present invention is characterized by comprising switching means whose phases can be controlled, and control means for controlling the phases of these switching means.

[0013]

[Operation] By controlling the phase of the switching means and shifting the phase of the AC voltage applied to the main winding and the auxiliary winding, a phase difference is created between the current in the main winding and the current in the auxiliary winding. A rotating magnetic field is generated between the main winding and the auxiliary winding, which generates a starting torque and starts the motor. Further, by controlling the phase of the switching means, the direction of the rotating magnetic field generated by the main winding and the auxiliary winding is changed, and the rotation direction of the motor is controlled.

[0014]

Embodiments Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 schematically shows the overall configuration of a single-phase induction motor drive device, FIG. 2 shows signals of various parts of the drive device during startup, and FIG. 3 shows signals of various parts of the drive device during stable operation after startup. In FIG. 1, the same parts as in the conventional example shown in FIG. 4 are given the same reference numerals, and detailed explanations are omitted.

In FIG. 1, the G terminals of two triacs (switching means) (2) and (3) are connected to a microcomputer (control means) (6) via current-limiting resistors (8) and (9), respectively. has been done.

The zero cross detection circuit (7) consists of a transistor (10) and two resistors (11) and (12), and the base of the transistor (10) is connected to one terminal of the AC power supply (4) through the resistor (11). The emitter of the transistor (10) is connected to the other terminal of the AC power supply (4). In addition, a circuit DC power supply (13) and a resistor (
12) are connected in series, and the transistor (10)
The collector and the negative terminal of the DC power supply (13) are connected to the microcomputer (6).

In FIGS. 2 and 3, (a) shows the power supply voltage VDA (voltage between D and A) of the AC power supply (4), (b
) is the output voltage VGD (
G-D voltage), (c) is the first voltage from the microcomputer (6).
The command voltage VED (voltage between E-D) to the triac (2), (d) is the applied voltage VBA (B-
A voltage), (e) is the command voltage VFD from the microcomputer (6) to the second triac (3) (F-D voltage)
, (f) is the applied voltage VCA(C-
voltage between A).

Output voltage V of zero cross detection circuit (7)
GD turns on every time the power supply voltage VDA becomes 0 (
(See Figure 2(b) and Figure 3(b)). Microcomputer (6
) is the output voltage VGD of the zero cross detection circuit (7)
By detecting that the triacs (2) and (3) are turned on, the timing to start the phase control of the triacs (2) and (3) is known, and as explained next, by controlling the phase of the triacs (2) and (3), the motor (1) Performs rotation direction control, starting, and operation after starting.

When the motor (1) is stopped, command voltages VED and VFD to the two triacs (2) and (3) are both off.

When the motor (1) is rotated in the forward direction, at the time of starting, the output voltage VGD of the zero cross detection circuit (7)
The command voltage VFD to the second triac (3) is turned on at the same time that the
), the predetermined phase angle θ after VGD is turned on.
At the time of delay, the command voltage V to the first triac (2)
Turn on ED (see Figure 2(c)). As a result, the power supply voltage VDA becomes 0 and the second triac (3
) is turned on, then the power supply voltage VDA is applied to the auxiliary winding (1b) until the power supply voltage VDA becomes 0, and as a result, the full wave of the power supply voltage VDA is applied to the auxiliary winding (1b). (See Figure 2(f)). In addition, the first triac (2
) is turned on, and then the power supply voltage VDA is applied to the main winding (1a) until the power supply voltage VDA becomes 0, and as a result, only the part after the phase angle θ of each half wave of the power supply voltage VDA is It is applied to the main winding (1a) (see Fig. 2(d)). Therefore, a current whose phase leads the main winding (1a) flows through the auxiliary winding (1b), and the main winding (1a) and the auxiliary winding (1a)
b) generates a rotating magnetic field in the forward rotational direction, generates a starting torque in the forward rotational direction, and starts the motor (1) in the forward rotational direction.

When the motor (1) starts in the forward rotation direction, the command voltage VFD to the second triac (3) is always turned off (see Fig. 3(e)), and the zero cross detection circuit (
7) At the same time as the output voltage VGD of turns on, that is, at a phase angle of 0 degrees, the command voltage V to the first triac (2) is applied.
Turn on the ED (see Figure 3(c)). As a result, the second triac (3) is always turned off,
No voltage is applied to the auxiliary winding (1b) (Fig. 3(
On the other hand, at the same time as the power supply voltage VDA becomes 0, the first triac (2) is turned on and the full wave of the power supply voltage VDA is applied to the main winding (1a) (see Figure 3(d)).
), this causes the motor (1) to continue rotating in the forward direction.

In this case, even after starting, the two triacs (2) and (3) may be controlled in the same way as at the time of starting.

When the motor (1) is rotated in reverse, the output voltage VG of the zero cross detection circuit (7) is
At the same time as D is turned on, that is, at a phase angle of 0 degrees, the command voltage VED to the first triac (2) is turned on, and VGD is turned on.
The command voltage VED to the second triac (3) is turned on at a delay of a predetermined phase angle θ after the second triac (3) is turned on. As a result, the first triac (2) is turned on at the same time as the power supply voltage VDA becomes 0, and the full wave of the power supply voltage VDA is applied to the main winding (1a). In addition, the power supply voltage VD
The second triac (3) is turned on when the phase angle θ lags after A becomes 0, and only the portion after the phase angle θ of each half wave of the power supply voltage VDA is applied to the auxiliary winding (1b). be done. Therefore, the main winding (1a) has an auxiliary winding (1b).
A current with a more advanced phase flows, and the main winding (1a) and auxiliary winding (1b) generate a rotating magnetic field in the opposite direction of rotation, generating a starting torque in the opposite direction of rotation, and the motor (1) rotates in the opposite direction. Start in the direction of rotation.

When the motor (1) starts in the reverse rotation direction, the command voltage VFD to the second triac (3) is always turned off (Fig. 3(e)), as in the case of forward rotation.
), output voltage VG of zero cross detection circuit (7)
At the same time that D is turned on, that is, at a phase angle of 0 degrees, the command voltage VED to the first triac (2) is turned on (see FIG. 3(c)), and the motor (1) continues to rotate in the reverse direction.

In this case as well, the two triacs (2) and (3) may be controlled in the same manner as at the time of starting even after starting.

If the command voltages VED and VFD to the two triacs (2) and (3) are turned off, the motor (1)
stops.

When the above-mentioned motor (1) is used in a hot/cold air blower, for example, cold air is blown out when the motor rotates in the forward direction, and hot air is blown out when the motor is rotated in the reverse direction.

The drive device of this embodiment can be realized by simply removing the phase-advance capacitor (5) from the conventional drive device shown in FIG. 4 and adding a control program to the microcomputer (6). Equipment can be provided.

[0030]

According to the drive device of the present invention, it is possible to start and control the rotational direction of a single-phase induction motor without using a phase advance capacitor, and the cost of the device can be reduced, making it economical.

[Brief explanation of the drawing]

FIG. 1 is an electrical circuit diagram of a single-phase induction motor drive device showing an embodiment of the present invention.

FIG. 2 is a time chart showing voltages at various parts of the drive device when starting the motor.

FIG. 3 is a time chart showing voltages at various parts of the drive device during stable operation after the motor is started.

FIG. 4 is an electrical block diagram of a conventional single-phase induction motor drive device.

[Explanation of symbols]

(1) Single-phase induction motor (1a)
Main winding

Claims (1)

[Claims] [Claim 1] Phase-controllable switching means connected in series to a main winding and an auxiliary winding of a single-phase induction motor connected in parallel to a single-phase AC power supply, and controlling the phase of these switching means. A driving device for a single-phase induction motor, characterized in that it is equipped with a control means for controlling a single-phase induction motor.