JPH0435998B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Field of Industrial Application> The present invention relates to a load current control circuit for electric fans and other various induction devices.

<Prior art> Conventionally, the number of circuits in electric fans or other AC induction equipment was controlled by changing the input voltage or current, but these methods were limited by current limiting with resistors or voltage terminals. This was due to the switch.

<Problems to be Solved by the Invention> However, all of these methods rely on mechanical operation, and they often cause poor contact or damage due to friction, leading to various failures during long-term use. was. Furthermore, it has been structurally difficult to downsize.

The present invention provides a load current control circuit that does not rely on mechanical operation, is easily miniaturized, and has fewer failures.

<Means for solving the problem> Consists of an inductive load having one or more lead-out terminals, semiconductor switching elements connected to each of the terminals, and a microcomputer that selectively controls the semiconductor switching elements. By changing the ratio of current flowing to adjacent terminals, the rotational speed corresponding to each terminal and the rotational speed in the other intermediate region can be obtained.

<Operation> Using a half cycle of AC power supplied to an inductive load as a unit of control amount, a microcomputer assigns a different control amount to each terminal of the inductive load, and each terminal is assigned a different control amount by the operation of a semiconductor switching element. The current flow to each terminal is selectively controlled, and the rotational speed of parts other than the terminals is generated depending on the current flow ratio to the adjacent terminals.

<Embodiments> The present invention will be described in detail below with reference to embodiments shown in the drawings.The present invention is intended to control the load by providing a tap in the inductive load of an AC device and controlling the amount of current supplied to the tap. This method is intended to be applied to motors and other inductive loads in general, but here we will explain the speed control of an electric fan as an example.

FIG. 1 shows a specific example of the control circuit of the present invention, in which an AC power supply 1 is converted into a DC power supply by a power supply circuit 5 consisting of a diode 2, a Zener diode 3, and a PNP transistor 4.
Both terminals of the secondary side of a photocoupler 6 suitably connected between both terminals of the AC power supply 1 are connected between the DC power supply via resistors 7 and 8, respectively, and the base emitter of the NPN transistor 9 is connected to both ends of the resistor 7. Applicable
The collector of the NPN transistor 9 is connected to the positive side of the DC power supply via the collector resistor 10, and the collector of the NPN transistor 9 is used as the zero-cross detection pulse output terminal of the AC power supply to the microcomputer 11.
It is connected to the CLK terminal to generate a pulse-like signal as shown in FIG. 3B at the zero cross point that occurs every half cycle of the AC power waveform shown as A in FIGS. 3a and 3b.

Then, the positive and negative sides of the DC power supply are connected to the VDD and VSS terminals of the microcomputer 11, respectively, and the reset circuit 13 is connected to the reset terminal RST of the microcomputer 11. When the power is turned on, a power-on reset is applied, and the oscillation circuit 14 is connected to the OSC terminal.

Then, a push-on switch 12 is inserted between the IN terminal and the positive side of the DC power supply, and the switch 1
The rotational speed of the fan is configured to be changed each time 2 is repeatedly pressed.

On the other hand, the microcomputer 11
Tap out1 (H: high speed) of fan motor 16
Connect with the gate of triax 13 connected to H', operate the gate, and similarly out2 (M:
Connect the terminal of out3 (medium speed) to the gate of triax 14 connected to tap M', and then connect the terminal of out3 (L: low speed)
By connecting the terminal of 1 to the gate of the triax 15 connected to tap L', each gate can be operated. In the microcomputer 11, descriptions of ports not directly related to the present invention have been omitted, but the configuration of the main parts is as described above.

Next, referring to the flowchart of FIG. 2 for the above configuration, the rotational speed of the fan motor 2 is
Assuming that there are 7 stages of V ₁ , V, ..., V ₇ ,
Judge which of these speeds to select and select triaxes 13, 14, and 1 according to the respective fan speeds.
Conductivity is selectively controlled for any one of 5.

For example, if the fan speed is V ₁ ,
Triac 15 is attempted to be controlled by the output of out3. That is, the pulse signal B is input to the CLK terminal of the microcomputer 11 after waiting for the arrival of the zero cross of the AC power supply A. Then, in the microcomputer 11, the pulse signal B is outputted from the out3 terminal as the gate signal of the triax 15, so that the triax 15 is turned "ON" and becomes conductive, and starts rising from the point of zero cross of the AC power supply. do. The current flowing through the triax 15 is continuously conducted using a half cycle of the AC power supply as a unit of control amount. At the same time, the outputs from out1 and out2 are stopped on the other hand. Next to this state, the "ON" state of the push-on switch 12 is read, and if the push-on switch 12 is not pushed, the fan speed V ₁ is maintained, and the fan motor 1 is
6 and press the switch 12 at this time to shift to another speed. For example, fan speed V ₄ (M:
The fan speed V ₇ (H: high speed) is also the same as the fan speed V ₁ . That is, when the fan speed V ₄ is selected by operating the push-on switch 12, the gate of the triax 14 is operated by the output from out2, the conduction of only the triax 14 is promoted, and the fan motor 16 is rotated at a medium speed. , Similarly, if the fan speed is V ₇ , the output from out 1 only conducts the drying gas 13, and the fan motor 16
rotate at high speed.

Therefore, the taps L', M' of the fan motor 16,
In the case of the rotational speeds V ₁ , V ₄ , and V ₇ corresponding to H′, speed conversion is possible by simply selecting one of the triaxes 13, 14, and 15, but apart from the above, in the case of the fan speed V ₂ Tap M′ (medium speed) and L′ (low speed)
As shown in FIG. 3a, current is supplied to both of them at an energization ratio of M':L'=2:3, using the half cycle of the AC power supply as a unit of control amount. That is, at fan speed V ₂ , the M counter determines whether or not a half cycle of current is conducted twice,
If it is “N(NO)”, add 1 to the M counter and conduct the triax 14 until the M counter becomes 2.
Electrify medium speed tap M'.

In other words, if the M counter is M≠2, the triax 14 is turned on, but other operations depend on the fan speed.
Go through the main routine similar to V ₁ .

However, the M counter shows "Y" (YES) when M=2.
If so, the conduction of the triac 14 is stopped, and at the same time, a control pulse is output from out3, and the conduction of the triac 15 is started. Then, a control pulse is input from out3 to the triax 15 until the L counter reaches 3, and three half-cycles of current are passed through. When the L counter reaches 3, the operation of the L counter is stopped, so the triax 15 is disabled. It becomes conductive, and at the same time, a control pulse for the triac 14 is output again from out2 of the microcomputer 11. In this way, each time a predetermined conduction rotation determined for each fan speed is counted, the adjacent triaxes 14 and 15 are alternately switched and energized, thereby reducing the current flowing through the two triaxes 14 and 15. The rotational speed V ₂ of the fan motor 16 is determined by the conduction ratio of .

That is, the rotational speed _V2 is an intermediate speed between when only the triax 14 is energized at 100% and when only the triax 15 is energized and rotated at 100%.

Also, in the case of fan speed V ₆ , as in the case of fan speed V _2, the amount of current applied to the high-speed tap H' is controlled by the triax 13 as shown in Fig. 3b, and the AC power supply is cycled for half a cycle. This can easily be obtained by setting the conduction ratio so that the amount of current supplied to the medium-speed tap M' becomes two half cycles by controlling the triax 14.

In the flowchart of Figure 2,
Although the explanation of the fan speeds V ₃ , V ₄ , and V ₅ has been omitted, the fan speed V ₄ is the same as the fan speeds V ₁ and V ₇ , and the fan speeds V ₃ and V _{5 are the same as the fan speeds V 1 and V 7} .
It is exactly the same as in the case of V ₂ and V ₆ . In addition, in the above case, when there is a control output at out1, the microcomputer 11 acts so that there is no control output from out2 and out3, and this is achieved so that two or more triacs will not be in the "ON" state at the same time. ing.

In addition, FIG. 3a shows a time chart when the fan speed is _V2 , and A and B show the AC power waveform and pulse waveform, respectively, as described above, and C shows the tap H from the triac 13. The current waveform flowing to ', D is the tap from triax 14.
The waveform of the current flowing to M' is shown, and E is the waveform of the current flowing from the triac 15 to the tap L'.

Further, FIG. 4 is a characteristic diagram showing the relationship between the conduction ratio of the current flowing through each triax and the rotational speed of the fan motor 16.

Therefore, as is clear from the above characteristic diagram, speed conversion is possible by changing the conduction ratio of the current flowing through the triax between the maximum rotation speed and the minimum rotation speed of the fan motor 16.

The present invention is configured as described above, and although the above example describes the case where two taps are provided in the middle of the inductive load, one or three or more taps may be provided in addition to this. By providing a large number of them, speed control can be made more precise.

<Effects of the Invention> By configuring as described above, there are no mechanically operated parts, significantly reducing failures and improving reliability.

Furthermore, since there are no mechanical components, miniaturization is extremely easy. In addition, the manufacturing process can be simplified and managed easily, and manufacturing costs can be significantly reduced accordingly.

In addition, the amount of conduction per time flowing through the triax was set within 10 in half cycle units, and the conduction ratio was set to 3:2, but it is not limited to this, and there is no problem in the configuration even if it is 30:20. In operation, the conduction period of one triax increases accordingly, and in the fan motor of the above example, electromagnetic noise and wind noise increase, reducing the commercial value.In the present invention, the conduction period is short. This makes it more comfortable with less noise caused by load fluctuations. Furthermore, on/
Unlike wave number control by turning it off, since it is always controlled in the on state, there is no torsional vibration or vibration in the front-rear direction, and extremely stable rotation can be obtained. In addition, multi-stage shifting is possible with a small number of gear shifting terminals.

In addition, the above-mentioned control circuit can be widely applied not only to rotation control of a fan motor but also to any inductive load, and has many excellent effects such as being a highly versatile control circuit.

[Brief explanation of drawings]

FIG. 1 is a wiring diagram showing the main parts of the control circuit of the present invention;
Figure 2 is a diagram showing a flowchart, Figure 3a,
4b is a diagram showing a time chart of the AC power supply and the current supplied to each triax, and FIG. 4 is a characteristic diagram showing the relationship between the conduction ratio of the triac and the rotational speed of the fan motor. 11... Microcomputer, 12... Push-on switch, 13, 14, 15... Triax, 16... Fan motor, H', M', L'...
...Tap (terminal).

Claims (1)

[Claims] 1. An induction motor having one or more speed change terminals, a semiconductor switching element connected to each speed change terminal of the induction motor, and a control pulse applied to the gate circuit of the semiconductor switching element by manual operation of an instruction switch. It consists of a microcomputer that outputs an output, and by manual operation of the instruction switch, the output of the microcomputer changes the energization ratio to each speed change terminal provided on the induction motor, and always energizes one of the speed change terminals. Along with letting
A speed control circuit for a fan motor of an electric fan, characterized in that the current flowing to each speed-changing terminal is controlled at a zero-crossing point, and the control is performed using a half cycle of a sine power supply current wave as the minimum unit.