JPH02247931A - Contact or driving circuit - Google Patents

Abstract

PURPOSE:To save electric power by reducing the holding power of a contactor by installing an adder to find a logical sum of an output of a mono-multi part and an output signal of an oscillator and a driving part to flow a current to a contactor corresponding to an output signal of the adder. CONSTITUTION:In the case of a two-ways switch, input and output are ON when a high level input is given to a control terminal C. When a micro-switch 1 is ON, the two-ways switch IC3 is always ON between input and output when a micro-switch is ON if a signal (b) is given. A signal (g) is given, therefore, to the input side of a photo coupler PC2 as it is, and an output signal (h) occurs at the photo coupler PC2. A driving element PMOS becomes ON corresponding to the signal (h), and flows a current Ir corresponding to the signal (h) from a battery E through a contactor 2. A diode Di is connected in parallel to the coil 21 of the contactor, and a current flows through the diode Di by means of a reverse power generated at at the coil 21 while the signal (h) is OFF. Thereby, a large current flows at the initial time of operation, and after operation, such a small current as required for holding flows.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a circuit for driving a contactor (or relay), and particularly to a contactor drive circuit that enables reduction of electric power required to drive a contactor, etc. It is related to.

[Conventional technology]

Conventionally, as a circuit for driving a contactor or a relay, a method is generally used in which a micro switch (M, SW) or the like is used and the circuit is driven by turning it on and off.

FIG. 3 shows a conventional contactor drive circuit.

Micro switch (M, 5W) 1 is its contact (No)
By turning on the power source E consisting of a battery etc.
A current flows from the coil 21 of the contactor 2 to the coil 21 of the contactor 2. This causes the contactor 2 to operate and its contacts 22 to switch. Note that the diode Di is a microswitch l.
This is provided to release the energy stored in the coil 21 when the coil 21 is turned off.

[Problem to be solved by the invention]

Generally, when operating a contactor or relay, a large amount of power is required when the movable contact initially moves from the NC (normally closed) side to the fJ'no (normally open) side, but once the switching is done - After that,
A large amount of power is not required to maintain the holding state, and it is sufficient to flow a current of 20 to 30% of the initial current.

Therefore, it is not only wasteful to continue flowing a current of a value necessary for the initial operation of the contactor etc. even after operation, but also causes problems such as insulation deterioration due to overheating of the coil.

In particular, in the case of an electric vehicle such as an electric wheelchair, a battery that is a power source for driving a contactor is often configured to be charged from the main battery of the electric vehicle via a DC-DC converter exclusively for charging.

In such a case, the battery terminal voltage is selected to be, for example, about 20% higher than the rated voltage of the contactor coil, so the problem of overheating is more likely to occur.

[Purpose of the invention]

The present invention aims to solve the problems of the prior art, and is a contactor drive method that reduces the current in the holding state in the contactor to save power and prevents the coil from overheating. Its purpose is to clean the circuit.

[Means to solve the problem]

In a contactor drive circuit that energizes a contactor in response to the operation of a control switch, a mono-multi section that generates a continuous signal of a predetermined length of time in response to the operation of the control switch;
An oscillation section that generates an intermittent wave signal in response to the operation of the control switch, and an addition section that calculates the logical sum of the output signal of the monomulti section and the output signal of the oscillation section are provided. and,
A configuration is adopted in which a drive unit is provided that energizes the contactor in accordance with the output signal of the adder. This aims to achieve the above-mentioned purpose.

[Embodiments of the invention]

FIG. 1 shows one embodiment of the present invention, and FIG.
A monomulti section 39, an oscillating section 4, an adding section 5, and a driving section 6 are provided for the microswitch 1 and contactor 2 similar to those in the figure.

The mono-multi unit 3 includes a photocoupler Pct and a monostable multi-by-break (hereinafter referred to as "
Mono-Multi J) is equipped with ICI.

The oscillator 4 includes a timer IC 5 that generates an intermittent wave signal of a predetermined frequency.

The adder 5 includes bidirectional switches IC2 to IC4 made of semiconductor elements that turn on and off between input and output according to a control signal;
It consists of diodes DI and D2 forming an OR circuit. The drive unit 6 includes a photocoupler PC2 and a drive element PMO3 made of a power MOS FET that controls an output current according to an input signal.

Moreover, the power supply part PS consists of a DC-DC converter, and is supplied with a constant voltage ■ from the battery power supply E. occurs.

FIG. 2 shows signals of various parts in the circuit of FIG. 1, and is used to explain the operation of the contactor drive circuit of the present invention.

In this Figure 2, the symbol a indicates the operation of the microswitch l, and the symbol is the output signal of the photocoupler PCI (c and d are the output signals of the monomultiple C1, and e is the output signal of the bidirectional switch IC2). The input signal, f is the output signal of the timer IC5, g is the input signal of the bidirectional switch IC3, h is the output signal of the photocoupler PC2, l is the current of the coil 21 of the contactor 2, and l is the current of the drive element PMO3, respectively. show.

The microswitch 1 operates in conjunction with the accelerator of the electric vehicle, and is switched from the NC side to the NC side at point A when the accelerator is slightly depressed (FIG. 2a).

As a result, a current flows through the resistor R1 to the input side of the photocoupler PCI, and an output signal S is generated at the resistor R2. This signal is applied as a trigger input to the monomulti ICI, and is also applied to the control terminal C of the bidirectional switch IC3.

The monomulti ICI is activated by the rising edge of the signal S, and the time determined by the resistor R3 and capacitor C1,
Signal d at terminal 0 becomes high level (H), and signal C at terminal O becomes low level (L). Signal C is from bidirectional switch IC4, and signal d is from bidirectional switch IC.
2 to respective control terminals C.

The timer IC5 continuously generates an output signal consisting of an intermittent wave of a constant frequency when the power supply Vcc is applied, and the frequency and conduction ratio are determined by external resistors R7 and R8.
and contactor C2.

A bidirectional switch is one in which input and output are turned on when a high level input is applied to a control terminal C. The bidirectional switch IC2 is given a constant voltage ycc as an input signal e, and the bidirectional switch IC4 is given the output signal of the timer IC5 as an input signal f, and the respective output signals are connected to diodes DI and D2. Since the output signal g is logically summed through the monomultiple I
It remains high level continuously during the operating period of CI, and after the period ends, it alternately becomes high level, low level, and null.

On the other hand, the bidirectional switch IC3 is supplied with a signal so that when the microswitch 1 is on, the input and output are always on. Therefore, the signal g is directly applied to the input side of the photocoupler PC2, and thereby the photocoupler PC2 produces an output signal.

The drive element PMO3, which is a power MOS FET, is turned on in response to the signal and causes a current ip corresponding to the input signal to flow from the battery E through the contactor 2. A diode Di is connected in parallel to the coil 21 of the contactor 2. By causing a current to flow through the diode Di due to the back electromotive force generated in the coil 21 during the period when the signal is off, a current as shown in FIG. 2i is generated in the coil 21.

In the circuit of FIG. 2, the photocoupler PCI.

The PC2 is used because a control circuit isolated from the battery E is required in the case of an electric vehicle or the like. Similarly, the power supply part PS also has a constant voltage VC independent from the battery power supply E.
It is used to obtain C.

〔Effect of the invention〕

As explained above, according to the present invention, in the contactor or relay drive circuit, it is possible to control the contactor or relay drive circuit so that a sufficiently large current flows at the initial stage of operation, and after the operation, a small current necessary for holding the contactor or relay flows. can. by this,
Power consumption in the contactor or relay drive circuit can be significantly reduced, heat generation in the contactor coil can be reduced, insulation deterioration due to overheating can be prevented, and reliability can be improved. Moreover, this makes it possible to provide a contactor drive circuit that is unprecedented and superior in that it can suppress a temperature rise inside a sealed control circuit of an electric vehicle or the like.

This is a diagram.

1... Micro switch (M, SW), 2... Contactor, 3... Mono multi section, 4... Oscillation section, 5
... Adding section, 6... Drive section, 21... Contactor coil, PCI, PC2... Photocoupler, ICI・
・Monostable multivibrator (mono multi), IC2
~IC4...bidirectional switch, PMO3...drive element, PS...power supply section, Dl, D2. Di...Diode, R1 to R8...Resistor, C1, C2...Capacitor.

Claims (1)

[Claims] (1) In a contactor drive circuit that energizes a contactor in response to the operation of a control switch, there is a monomulti section that generates a continuous signal of a certain length of time in response to the operation of the control switch, and the operation of the control switch. an oscillation section that generates an intermittent wave signal in response to the above, and an addition section that calculates the logical sum of the output signal of the monomulti section and the output signal of the oscillation section,
A contactor drive circuit comprising: a drive section that energizes the contactor in accordance with an output signal of the adder.