JPS62196091A - Power controller - Google Patents

Abstract

PURPOSE:To secure starting compensation, by a method wherein a phase control circuit is short-circuited between input and output during starting operation of a three-phase induction motor. CONSTITUTION:When a power switch 11 is turned on and a motor 13 out of operation is supplied with power, timers 24, 26 output control signals respectively for times T1, T2 (T1>T2) by detection signal of a starting detection circuit 22. Thereby, first a triac 14 is rendered entirely conductive. Next, after operation delay time, relay contact of a short-circuited circuit 20 is closed and at the same time the triac 14 is turned off. After lapse of the time T1, the relay contact of the short-circuited circuit 20 is opened and the triac 14 is again rendered entirely conductive. After lapse of the time T2, the triac 14 is fired at a prescribed conduction angle by a trigger circuit 16.

Description

DETAILED DESCRIPTION OF THE INVENTION "Field of Industrial Application" The present invention relates to a power controller, and in particular, to a power controller for controlling the rotation of a load-side electrical device such as an induction motor or a fluorescent lamp. i
This invention relates to a power controller equipped with equipment that causes difficulty in starting when a voltage lower than the rated voltage is applied through phase control for power control, dimming, etc.

``Prior Art'' The voltage supplied to an electric motor is varied by phase control using a thyristor or transistor to control the rotation of a fan, etc., or to save power in a refrigeration compressor motor, etc.

However, when starting an induction motor, the starting torque is insufficient at a low voltage due to phase control, which may cause a rotation lock phenomenon, difficulty in starting, or burnout of the motor.

For this reason, conventionally, in order to smooth the startup of fans, etc., a startup compensation gate circuit including a capacitor, diode, resistor, etc. with a large capacity of several tens of gF has been installed in addition to the gate circuit for rotation control. I was doing it.

"Problems to be Solved by the Invention" However, in the conventional technology, the power supply voltage is directly applied to the motor immediately after the power is turned on, but after that, even though the motor is still in the process of starting up, First, as the capacitor of large capacity in the gate circuit for start-up compensation progresses, the voltage applied to the motor suddenly decreases.

For this reason, if the mechanical load coupled to the motor is large, the torque generated by the motor is insufficient during startup, causing various startup problems such as the motor stopping once it has started rotating or generating large vibrations. was there.

Therefore, with relatively large fans, rotation control can only be performed within a small range, and with refrigeration compressor motors, power saving control is not possible.

Furthermore, when attempting to perform reliable startup compensation using conventional technology,
A capacitor having an extremely large capacity and a predetermined withstand voltage must be used, which is difficult to realize in terms of cost.

Furthermore, induction motors and other motors draw a large amount of current when they are started, so even if they can be started smoothly, large motors lack the withstand voltage and current capacity of power control elements such as thyristors, making it difficult to perform phase control. There was a problem.

In view of the drawbacks of the prior art, the present invention provides a power source that can reliably compensate for the starting of an induction motor, etc., and that does not cause problems such as destruction of the power control element F- even when a large starting current flows. Its purpose is to provide a controller.

[Means for solving the problem] The power controller according to the present invention includes a startup detection circuit that detects the startup of a load-side electrical device, and a detection signal from the startup detection circuit that detects when the load-side electrical device is being started. It is equipped with a mechanical short circuit that shorts between the input and output of the phase control circuit, and a short circuit open timing detection circuit that detects the time before and after the short circuit changes from short circuit to open. The output phase control circuit is controlled so that the amount of phase control by the one-phase control circuit is made small or zero before and after the short circuit changes from short to open.

"Example" Next, one embodiment of the present invention will be described with reference to FIG.

A power supply 10 is connected to a load 12 consisting of a power-on switch 11 and a motor 13 for a refrigeration compressor, and a power switch 14 is connected thereto, and a phase control circuit 18 for power saving control, for example, comprises a trigger circuit 1B for varying the phase angle of the power switch 14. is equipped with.

The trigger circuit 16 is of a current synchronous type including, for example, a CR circuit, and by varying the magnitude of R, the phase angle of the triac 14 is varied and the output voltage is varied. Furthermore, when the first control signal is input from the outside, the trigger circuit 16 is configured to short-circuit R so that the conduction angle of the triac 14 is approximately 100% of the maximum while inputting the control signal. .

When the conduction angle of the triac 14 becomes approximately 100%, the output waveform of the triac 14 becomes a sine wave, and the input voltage is output as is.

A relay set short circuit 20 is connected in parallel to both ends of the triac 14. While the motor 13 is being started, the short circuit 20 shorts the triac 14 to release phase control, applies the power supply voltage to the motor 13 as it is, generates a large starting torque, and ensures smooth startup. This is to prevent a large current from being applied to the triac 14 by flowing a starting current to the triac 14, thereby preventing the triac 14 from being destroyed.

By using the short circuit 20 as a relay set, the short circuit 20 with a large capacity can be constructed at low cost.

The relay contact of the short circuit 20 is normally open, and when a second control signal is input from the outside, the relay contact closes while the second control signal is input.

However, in the short circuit 20 of the relay set, if the triac 14 does not enter the conduction period at the moment the relay contact changes from the closed state to the open state, the power supply system will temporarily disconnect from the machine when the relay contact changes from closed to open. In an attempt to suppress the discontinuous change in current, a large amount of energy stored in the voltage components on the power supply side and load side is released, causing an arc to jump to the relay contacts, damaging the relay contacts and causing a short circuit. The lifespan of the 20 may be shortened, or a short circuit may occur after using the 20 for - times.
may be broken.

For this reason, in this embodiment, as described above, the triac circuit 16 is controlled by the first signal applied from the outside, and after the short circuit 20 is activated, the relay contact changes from closed to open and the main circuit is switched to the triac 14. At the moment the triac 14 breaks, the phase of the triac 14 is controlled at almost 100% conduction angle to prevent the power supply system from opening when the relay contact changes from closed to open, thereby eliminating contact arcing. That's what I do.

The short circuit 20 is connected to a starting operation detection circuit 21, and is configured to input the starting operation detection output of the motor 13 from the starting operation detection circuit 21 as a second control signal.

The startup detection circuit 21 includes a startup occurrence detection circuit 22 and a second timer 26 connected to the output side of the startup detection circuit 22. For example, when the detected current exceeds a predetermined level at the rise of the starting current flowing in the main circuit at the start of CT, the starting occurrence detection circuit 22 detects this with a level comparison circuit and outputs a starting occurrence detection signal. It is also possible to detect an instantaneous drop in the line voltage that occurs at the start of startup and output the startup occurrence detection signal, or to output the startup occurrence detection signal by a switch that is linked to the turning-on operation of the power-on switch 11.

The second timer 26 has a predetermined timer time T2 set in advance, and immediately outputs a second control signal to the short circuit 20 connected to the output side upon receiving the detection signal from the activation detection circuit 22.

The time required to almost complete the process, for example, the time T set in the IOS and during which the output of the second control signal continues.
2, it is assumed that the motor 13 is being activated.

A first timer 24 is connected to the trigger circuit 18,
A first control signal is input from this first timer 24.

The output side of the activation detection circuit 22 is also connected to a first timer 24 .

The first timer 24 has a predetermined time Tl set in advance, and immediately outputs the first control signal to the trigger circuit 16 connected to the output side when the detection number 191 is input from the activation detection circuit 22.

The time T1 is set longer than T2, for example, in IIS.

Therefore, by the combination of the activation occurrence detection circuit 22 and the first timer 24, the time before and after the relay of the short circuit 20 changes from closed to open is detected as the period during which the first control signal continues to be output. Become.

The second control output from the second timer 26 is stopped when a time T2 has elapsed since the second timer 26 was activated.

However, in the case of Daikichi μ, the operation of the relay short circuit 20 from open to close and from close to open is delayed by about 0.2 seconds from the start and stop of outputting the second control signal due to one mechanical delay.

Note that the second reactor installed in series with the main circuit is for suppressing the sudden rise of the starting current.
In addition, a bypass circuit consisting of a capacitor C1 and a resistor R1 connected in parallel to the reactor Ll and the triac 14 is used to bypass the rise of the starting current from the triac 14, and is used to supply power at the moment when the relay contact changes from closed to open. Even if a discontinuous change occurs in the current flowing through the circuit, the current is made to flow in a detour to reduce the current change and suppress the energy release due to the current component of the circuit.

C1゜The old value C1 is 0, which is used in a normal snubber circuit.
1 well F is about tens to hundreds, R1 is 5 so that the heat generation is small.
The value is approximately 0Ω to 200Ω, and is naturally selected to a value that allows the phase control circuit 18 to smoothly perform power saving control of the motor.

These, Ll, 2nd. C1 and R1 may be provided as necessary.

Next, the overall operation of the above embodiment will be explained.

Here, it is assumed that the load 12 side is made up of a plurality of power-on switches 11 and motors 13 connected in parallel, and one of the motors 13 is already in steady operation.

First, when the load 12 is in a steady state, the first timer 24
．． Neither the second timer 26 outputs a control signal.

Therefore, the contacts of the short circuit 20 are in an open state.

- On the other hand, the trigger circuit 16 applies a trigger pulse to the triac 14 at a predetermined timing determined by the constants of C and R, and performs phase control at a predetermined conduction angle smaller than 100%, when R of the OR circuit is not short-circuited. I will make you do it.

As a result, the output of the trigger 14 is reduced to, for example, about 85V, which is 15% lower than the power supply voltage toov, and power saving control of the load side motor 13 is performed.

When in such a power supply state, the power switch 1. When the power is turned on by turning on the switch 11, the startup occurrence detection circuit 22 immediately detects this and sends the detection signal to the first. Output to the second timer 24.26.

1st. Immediately upon inputting the detection signal, the m2 timers 24 and 28 start the first. The second control signal trigger circuit 16, short circuit 2
Output to 0.

As mentioned above, the short circuit 20 uses the ff12 control signal to close the relay contacts and short-circuit both ends of the triac 14. However, due to the mechanical operation, the short circuit 20 closes the relay contacts by using the ff12 control signal and shorts both ends of the triac 14. There will be delays.

On the other hand, if the H of the trigger circuit 16 is short-circuited by a semiconductor switch using a thyristor or a diode, the conduction angle of the trigger circuit 16 reaches 100% almost at the same time as the first control signal is input.
Therefore, if there is a non-conducting period in the triac 14 for 0.2 seconds, there is a risk that the triac 14 will generate large noise due to intermittent startup current or break down due to a surge, but this is prevented.

In addition, the starting current flowing through the triac 14 during the 0.2 seconds is suppressed by the accelerators Ll and L2, and is reduced by the detour of the bypass circuit 28, and the time is as short as 0.2 seconds. 14 is safe.

When the relay contact closes, the triac 14 is turned off, and the voltage supplied from the voltage #i10 is directly applied to the load 12 through the short circuit 20 for a predetermined period of time. At this time, the first control signal continues to be output.

Furthermore, the magnitude of the starting current at the moment the relay contact closes is suppressed by Ll, L2, etc., and the level of back electromotive force generated is smaller than when the contact is open, so the contact will not be damaged when the contact closes. .

By applying the power supply voltage to the load 12, the motor 13, which has been turned on by the closing switch 11, generates a large starting torque and starts rotating, and the large power supply voltage is continuously applied for a while. Therefore, acceleration is performed with a sufficiently large torque against the mechanical load coupled to the motor 13, and steady operation is quickly achieved! The rotation speed increases by 2' until E.

Moreover, since all the large starting current that flows during the starting operation of the motor 13 after the relay contact closes flows through the short circuit 20, the torch 14 is protected.

After the power-on switch 11 is turned on, the second control signal output from the second timer 26 stops when the time Tl for the motor 13 to reach a substantially steady operating state, for example, IO8, has elapsed. Therefore, the relay connection of the short circuit 20 changes from closed to open.

The moment the relay contact changes from closed to open, the triac 14
A voltage from the power supply is applied to the current synchronous trigger circuit 16. At this time, since the first control signal is still being input to the trigger circuit 16, R of the OR circuit in the trigger circuit 1 immediately becomes short-circuited, and the trigger 14 is also immediately triggered, making the triac 14 conductive. state.

Then, phase control is performed at a conduction angle of approximately 100x until the first control signal input stops, and the input from the power supply 10, for example 100V, is output as is to the load side.

Therefore, even if the relay contact changes from closed to open, the switch 14 will turn on from that moment, so there will be no discontinuous change in the current seen in the entire power supply system, and therefore the current will not change between the relay contacts. There is no energy released from the circuit components, and contact arcs do not fly.

Also, after the relay contact changes from closed to open, the trier
Even if a very short time lag occurs for some reason until the circuit 14 becomes conductive, the presence of the bypass circuit 28 prevents the power supply system from becoming open, thus suppressing discontinuous changes in the current. Therefore, the relay contacts will not be damaged.

Thereafter, when 12 hours have passed since the start of the motor 13, the first control signal output from the first timer 24 is stopped, and for example, one second after the short circuit 20 is opened, the triac L4 returns to the original phase control state. , for example, if the output voltage is 8
The voltage is lowered to 5V, and the power saving control of the motor 13 that was being performed until then is restarted.

The motor for the refrigeration compressor can achieve a large power saving effect by operating steadily at a lower voltage than when starting at the rated voltage.

In addition, in FIG. 1, the load 12 is the power-on switch 11.
Even if the motor 13 is configured independently, the same operation as described in 111 is performed.

Here, the first timer 61 control signal output is.

For example, 8S after the detection signal input to start the motor.
After the short circuit opens 10 seconds after the detection signal is input, the first control signal output may be stopped after the IIS, in short, when the short circuit changes the contact from closed to open. It is sufficient if it is output before and after switching to .

Therefore, instead of operating the first timer based on the detection output of the activation detection circuit, for example, a rotation speed sensor 30 is attached to the motor 13 as shown in FIG.
A mid-start determination circuit 32 is connected to the output side of 0, and the mid-start determination circuit 32 determines when the rotation speed of the motor 13 exceeds a predetermined level that is greater than zero and lower than the rotation speed during steady rotation. 20 (sufficiently before the switch changes from closed to open), this detection signal input temperature measurement 1 timer 34 is immediately activated, and the first control A, No. 1 having a duration extending before and after the relay is opened is output. It's okay.

Further, as shown in FIG. 2, the start-up operation detection circuit 40 also uses the start-up occurrence detection circuit 42, the start-up completion detection circuit 44, and their detection outputs, without using the second timer. This starting operation period detection circuit 4B, which may be composed of a starting operation period detection circuit 46 which outputs a second control signal until the end of the start operation, can be formed using an R-S flip-flop.

Here, the start-up completion detection circuit 44 may be configured to detect the point in time when the rotational speed of the motor 13, which has been increased by 1 from, for example, zero, exceeds a predetermined level near the steady rotational speed.

Furthermore, when the load is a single motor or a plurality of motors operated simultaneously, the following configuration may be adopted. l! μchi,
As shown in FIG. 3, first, the short circuit 50 is a relay that is normally closed and becomes open while the second control signal is input manually.

A start-up operation completion detection circuit 52 is connected to this short circuit 50 so that a second control signal is manually input to the start-up operation detection circuit 50.

This start-up operation completion detection circuit 52 includes, for example, as shown in FIG. 3, a start-up occurrence detection circuit 54, a delay circuit 5B connected to the output side of this start-up occurrence detection circuit 54, and
R-S with S terminal connected to the output side of 1ff1 circuit 5B
It consists of a flip-flop 58.

The startup occurrence detection circuit 54 outputs a pulse-like detection signal to the delay circuit 56 when the motor 13 starts to start when the power supply switch 11 is turned on. The delay circuit 56 delays the manually applied pulse for a predetermined period of time, for example, by lO8 from when the motor 13 starts to almost finishes starting, and outputs R.
- Output to S flip-flop 5th.

The R-5 flip-flop 58 is set in advance, and when a pulse is manually applied, the state is reversed and a high-level second control signal is output from the Q terminal.

The short circuit 50 connects the motor 13 when the second control signal is input.
Assuming that the activation of has been completed, the relay contact, which was in the closed state until then, is opened.

On the other hand, as in the case of FIG. 1, for example, the first control signal that continues from the iSl timer 24 to the IIS after the motor 13 is started may be input to the trigger circuit 16.

When the operation of the motor 13 is stopped or low, this is detected by the operation stop detection circuit 60, which is constituted by a switch circuit that outputs a switch signal in conjunction with the opening operation of the power supply switch 11, and the R-S flip flop 5
By resetting 8, relay contact x is opened to prepare for the next motor start.

In the case of FIG. 3, since both ends of the triac 14 are short-circuited by the short circuit 50 before the motor 13 is started, the starting current that flows when the motor 13 is started does not flow through the total heat triac 14.

Therefore, the protection of the torch 14 becomes more reliable.

Further, the trigger circuit 16 shown in FIG. 1 has four diodes bridge-connected in a predetermined direction to the SCH which is turned on in response to the first control signal, as shown as a circuit 16A in FIG. 4, for example. A diode bridge is connected to both ends of a resistor RIO for varying the phase angle, and this resistor RIO, a small resistor R11, and a capacitor CIO are connected in series, and then connected to both ends of the triac 14, and a capacitor C1O and a resistor R
SBS between IO and gate terminal of tochiak 14
All you have to do is intervene.

As a modification of the trigger circuit 16, as shown as a trigger circuit 18B in FIG. 5, a capacitor C20, a variable resistor R20, and a small resistor R21 are connected in parallel to both ends of the triac 14, and a connection is made between the capacitor C20 and the T1r variable resistor R2Q. Connect to the gate terminal of the triac 14 through the SBS, and connect a diode bridge between the small resistor R21 and the gate terminal.
It is also possible to connect an SCR having a switch and turn on the SCR with the first control signal.

Furthermore, the scope of application of the present invention is of course not limited to single-phase or multi-phase applications.For example, for three-phase applications, two SCRs connected in anti-parallel to each phase may be used instead of a triac.
Or use an SCR and a diode connected in anti-parallel,
Furthermore, it goes without saying that it may be constructed using GTO or the like. In these cases, the trigger circuit may be changed as appropriate depending on the thyristor used.

In addition to the motor, the load-side electrical equipment may be a fluorescent lamp or a combination thereof.

As an example, FIG. 6 shows a circuit diagram in which the present invention is applied to a three-phase system.

A 5CR8G and a diode 68 are connected in anti-parallel for each phase between the power supplies υ, V, W and a load 64 consisting of a three-phase induction electric @SO such as a refrigeration compressor motor and its power supply switch 62. However, a phase control circuit 72 is interposed in which a trigger circuit 70 is connected to the gate terminal of 5CR8B to perform variable phase control of the conduction angle.

The trigger circuit 70 may be configured as shown in FIGS. 4 and 5, for example.

Before and after the phase control circuit 72, Ll and L2 as current reactors are provided as in FIG.
01, R between the power supply side and the phase control circuit 72 and L2.
A bypass circuit consisting of 1 is connected.

As mentioned above, these Ll, L2. CI, R
1 is optional.

A short circuit 74 similar to that shown in FIG. 1 is connected to both ends of each phase control circuit 72.

During startup of the three-phase induction motor 60, a startup operation detection circuit 8 consisting of a startup occurrence detection circuit 76 and a second timer 78 connected to the output side of this startup occurrence detection circuit 76 is activated.
From 0, for example, a second control signal that continues for 10S from the start of motor activation is sent to each short circuit 74, their joints are closed, and the power supply voltage is applied to the motor 80 as is.

The output of the activation detection circuit 76 is also output to a first timer 82, and a first control signal output from the first timer 82, which continues for IIs after the start of motor activation, is sent to each trigger circuit 70, for example.

Therefore, as mentioned above, even if the motor 60 has finished starting and the short circuit 74 changes from closed to open, from that moment on, approximately IS
5CR8B of the phase control circuit 72 is in a conductive state IE for each phase.
, so there is no need to burn out the contacts.

2i'5 after IIS has passed since the motor 60 started starting.
1 control signal output is stopped, each phase control circuit 72 performs a predetermined phase control operation, and, for example, the 20GV power supply voltage is changed to 1.
This is learned from the motor 60 by reducing the voltage by 5% to 170V, causing the motor 60 to perform power-saving operation.

In addition, the load 64 side is the motor 60? In addition to being independent, for example, as shown in Fig. 6, in parallel with the motor 60 in the V and W phases,
It is also possible to connect the power supply switch 84 to the funeral phase fluorescent lamp fixture 8B, or to connect a three-phase fluorescent lamp rS fixture ae in parallel with the motor 60 to the U, V, and W phases, although there is no area. good.

Since a voltage lower than the rated power supply voltage of the fluorescent lamp A8B is applied to the fluorescent lamp 86 via the phase control circuit 72, the illuminance is reduced, but power is saved in the same way as on the motor 60 side.

Similarly to the motor 60, when the fluorescent lamp fixture 86 is initially turned on after the power supply switch 84 is turned on, it is difficult to turn it on at a low voltage due to phase control.

However, since the circuit shown in FIG. 6 includes a starting compensator, when the fluorescent lamp fixture 86 is initially turned on, the power supply voltage is applied for a predetermined period of time, and the initial lighting is performed smoothly.

When the load 64 is equipped with the motor 60 and the fluorescent lamp fixture 86,
The startup occurrence detection circuit 76 may be configured to be able to detect the start of startup of both. For example, it detects switch-related noise components that occur between the V and - phases at the moment the power-on switches 82 and 84 are closed. It may be configured by providing a noise sensor for sensing, a switch circuit that operates in conjunction with the closing operation of the power-on switches 82 and 84, and outputs a switch signal.

Then, a second timer 781 sets the start time of the motor 60 and the fluorescent lamp A86, whichever takes longer time to start up.
;The timer time T2 is set in advance, and 1.
The timer time T1 may be set in advance in the first timer 82 to be about 2 seconds longer.

This provides start-up compensation for both the motor 60 and the fluorescent light fixture 86, regardless of whether the other is in operation, and prevents contact damage when the short circuit 74 changes from closed to open. It will be done.

Furthermore, if an intermittent current is passed through the fluorescent lamp fixture 86 by phase control, the lighting may become unstable;
, R1, the fluorescent lamp fixture 8
6 is energized even during the non-conducting period of 5CR8B, a discharge current flows continuously, thus stabilizing the lighting.

"Effects of the Invention" As explained above, according to the present invention, the power supply voltage is applied to the electrical equipment on the load side, which is the target of phase control, during startup operation, so it is difficult to start up at low voltage. Even with IIm, it can be started smoothly, using a mechanical short circuit, which is 41% advantageous in terms of cost, and even if an excessive startup radio wave is generated, it bypasses the semiconductor element for power control, so the semiconductor element is not affected. This is an excellent system that does not require much effort, and furthermore, when a short circuit opens, the power supply system does not open, so the mechanical contacts are not damaged. have an effect.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram showing a power controller according to one embodiment of the present invention, FIG. 2 is a circuit diagram showing a power controller according to another embodiment of the present invention, and FIG. 3 is a circuit diagram showing a power controller according to another embodiment of the present invention. FIG. 4 is a circuit diagram showing an example of the trigger circuit in FIG. 1, FIG. 5 is a circuit diagram showing another example of the trigger circuit in FIG. FIG. 7 is a circuit diagram showing another embodiment. lO...Power source, 12...Load, 14...Triac, 16...Trigger circuit, 18...Phase control circuit, 20...Short circuit, 21...
...Start-up operation detection circuit, 24...First timer.

Claims (1)

[Claims] In a power controller that varies the power supply voltage using a phase control circuit and supplies it to electrical equipment on the load side, there is a startup detection circuit that detects the startup of the electrical equipment on the load side, and a detection signal from the startup detection circuit that detects the startup of the electrical equipment on the load side. A mechanical short circuit that shorts between the input and output of the phase control circuit during startup, and a short circuit open timing detection circuit that detects the period before and after the short circuit changes from the short circuit to the open state, A power controller characterized in that the detection signal controls the phase control circuit so that the phase control amount by the phase control circuit is made small or zero before and after the short circuit changes from a short circuit to an open state.