CN201479393U

CN201479393U - Circuit by utilizing bi-directional silicon controlled rectifier to control MCH heating body

Info

Publication number: CN201479393U
Application number: CN2009202085687U
Authority: CN
Inventors: 戴忠伟; 徐琦
Original assignee: BROADCHIP TECHNOLOGY GROUP Ltd
Current assignee: BROADCHIP TECHNOLOGY GROUP Ltd
Priority date: 2009-08-28
Filing date: 2009-08-28
Publication date: 2010-05-19
Anticipated expiration: 2019-08-28

Abstract

The utility model relates to a circuit by utilizing a bi-directional silicon controlled rectifier to control an MCH heating body, which comprises a DC power supply circuit, a control circuit and an AC power, and also comprises a bridge rectifier, wherein two input terminals of the bridge rectifier are connected with two output terminals of the AC power; a heating body is arranged on two terminals after being connected with a bi-directional silicon controlled rectifier in serial; one end of the DC power supply circuit is connected with one output terminal of the bridge rectifier, the other end of the DC power supply circuit is connected with a VDD terminal of the control circuit, and a GND terminal of the control circuit is connected with the other output terminal of the bridge rectifier; a first switch is also arranged between a first output terminal of the control circuit and the trigger terminal of the bi-directional silicon controlled rectifier; one end of a sampling resistor is connected with the junction point between the bi-directional silicon controlled rectifier and the heating body after being connected with a second switch in serial, and the other end is connected with the second output terminal of the control circuit; and the second switch is connected with the connection terminal of the sampling resistor and the input terminal of the control circuit. The circuit has the advantages that the power can be increased only through the full-wave heating on the premise that the resistance value is not reduced.

Description

Circuit with bidirectional triode thyristor control MCH heater

Technical field

The utility model relates to a kind of MCH heater, relates in particular to a kind of circuit of the MCH of control heater.

Background technology

MCH (cermet heater) heater has been widely used in the small household electrical appliance, and the characteristics of this heater maximum are that its resistance has ptc characteristics, and this makes people might utilize this characteristic to go to measure the working face temperature.The MCH heater not only can be used as heater but also can be used as temperature sensor in the product of heating like this, not only make the circuit of system and the installation of complete machine obtain simplifying, and because the installation site that does not have temperature sensor problem improperly, security of products also is greatly improved.But, in the temperature control product, to could determine current temperature by constantly the resistance of MCH being measured, because conventional method adopts one-way SCR to control, heat at the positive half cycle that adds alternating current, and negative half period carries out thermometric.For some products that need heat fast, the resistance value that reduces MCH with regard to having to adds high-power, but for small household electrical appliance, too little heater resistance can be brought very big trouble to crossing safety.

As shown in Figure 1: in the circuit of traditional one-way SCR control MCH heater, adding the positive half cycle of alternating current, the k1 closure, k2 opens, and control circuit provides triggering signal 1 and triggers unidirectional controllable silicon S CR, and heater is heated in this half cycle.Adding the negative half period of alternating current, k1 opens, and SCR no longer triggers, the k2 closure, and control circuit provides a direct voltage at output point 2, and by the dividing potential drop of sampling resistor RS and heater resistance R H, a voltage signal 3 is sampled.Among Fig. 2, provided a example with pulse-triggered SCR.There is an obvious problem in this circuit, is exactly heater all half-wave heating at alternating current forever, and power has only half of all-wave heating.

So a urgent demand pendulum is in face of the technical staff, having only by the all-wave heating to increase power under the prerequisite that does not reduce resistance value.

Summary of the invention

The utility model technical issues that need to address have provided a kind of circuit with bidirectional triode thyristor control MCH heater, are intended to solve the above problems.

In order to solve the problems of the technologies described above, the utility model is achieved through the following technical solutions:

The utility model comprises: DC power-supply circuit, control circuit and alternating current; Also comprise: a bridge heap; Input two ends of described bridge heap are exported two ends with alternating current and are linked to each other; Heater and bidirectional triode thyristor serial connection back are at two ends of alternating current; One end of DC power-supply circuit links to each other with an output of bridge heap, and the other end of DC power-supply circuit links to each other with the control circuit vdd terminal, and control circuit GND end links to each other with another output of bridge heap; Between control circuit first output and The Trigger of Bidirectional Triode Thyristor end, also comprise one first switch; Sampling resistor and second switch serial connection back one end are connected in bidirectional triode thyristor and heater tie point, and the other end is connected in control circuit second output; Second switch links to each other with the control circuit input with the sampling resistor link.

Compared with prior art, the beneficial effects of the utility model are: crossing the all-wave heating could increase power under the prerequisite that does not reduce resistance value.

Description of drawings

Fig. 1 is the circuit diagram of control MCH heater in the prior art;

Fig. 2 is the one-way SCR control MCH heater circuit timing diagram that adopts Fig. 1;

Fig. 3 is a circuit diagram of the present utility model;

Fig. 4 is the bidirectional triode thyristor control MCH heater circuit timing diagram that adopts Fig. 3;

Fig. 5 is that switch is the circuit diagram of diode among Fig. 3;

Fig. 6 is control circuit module figure among Fig. 3.

Embodiment

Below in conjunction with accompanying drawing and embodiment the utility model is described in further detail:

As seen from Figure 3: the utility model comprises: DC power-supply circuit, control circuit and alternating current; Also comprise: a bridge heap B; Input two ends of described bridge heap B are exported two ends (L, N) with alternating current and are linked to each other; Heater RH and bidirectional triode thyristor TRIAC serial connection back are at two ends of alternating current; One end of DC power-supply circuit links to each other with the output of bridge heap B, and the other end of DC power-supply circuit links to each other with the control circuit vdd terminal, and control circuit GND end links to each other with another output of bridge heap B; Between the trigger end 4 of control circuit first output 1 and bidirectional triode thyristor TRIAC, also comprise one first K switch 1; Sampling resistor RS and second switch K2 serial connection back one end are connected in bidirectional triode thyristor TRIAC and heater RH tie point 5, and the other end is connected in control circuit second output 2; Second switch K2 links to each other with control circuit input 3 with sampling resistor link 6.

Described first K switch 1 and second switch K2 are triode, relay or diode.

Please the control circuit of prior art is described? especially above-mentioned several ends of mentioning are explained.

The functional block diagram of control circuit is seen Fig. 6 among Fig. 3, control circuit is by comparator, temperature is set selector, and the output timing control circuit is formed, the signal (be temperature) of input 3 end input voltage sampled signals after sampling resistor RS and heater resistance R H dividing potential drop, the design temperature of setting in the selector by this signal and temperature relatively determines whether continuing heating.Result relatively triggers the silicon controlled signal in the output of 1 end, in 2 end output voltage sampled signals by behind the sequential control circuit.The temperature of this control circuit is set the visible patent ZL200620046719.X of specific descriptions of selection and comparator.In the utility model, the difference of control circuit is its sequential control circuit in control circuit and the prior art, because heater the time is the all-wave heating in heating in the utility model, so must close bidirectional triode thyristor TRIAC during thermometric.Concrete sequential is seen Fig. 4.

The utility model utilizes bidirectional triode thyristor to control the MCH heater, and its all-wave at alternating current is all heated.Bridge heap B powers to control circuit by DC power-supply circuit after to AC rectification, and heater RH and bidirectional triode thyristor TRIAC serial connection back are at the L and the N end of alternating current.At the k1 period of contact, k2 opens, and the output 1 of control circuit brings out trigger pulse triggers TRIAC, and heater all is heated in the alternating current positive-negative half-cycle.During thermometric, k1 is opened, and TRIAC stops to trigger.At the positive half cycle of alternating current, the k2 closure, direct voltage of output 2 ends output of control circuit, by the dividing potential drop of RS and RH, a voltage signal is sampled at control circuit input 3 ends.This voltage signal has reflected that the resistance value of current RH is a temperature value.

In this method, thermometric and to heat not be to carry out simultaneously is so heat and must stop during thermometric.Promptly in N cycle, have M cycle to be used for thermometric, other are used for heating.Like this, suppose that total power is Pfull, then actual power is

P＝M/N*Pfull

The value of M and N is considered the influence of flick in temperature sampling accuracy and the power product, and rule of thumb, N is preferably in 600ms between the 1s, and the value of M/N can reach 90% to 95%, though do not reach total power,, improve greatly compared with the power of the circuit of controlling with SCR 50%.And experience is also told people, and during heating to RH sampling, its sampling stability will sampling when stopping to heat.So the heating of 100% power is proved to be worthless.

The effect of the utility model jackshaft heap B can make the effectively isolated high pressure of control circuit, and heater directly is connected on the alternating current two ends rather than the purpose that is connected on bridge heap output is a electric current for the bridge heap that reduces to flow through.Because bridge is stored up in intermodulation distortion, the electric current of the bridge of flowing through heap is big more, and the conducted interference of product is just big more, and the bridge heap can not make the Electro Magnetic Compatibility of product better so the heater electric current is not flowed through.

K1 among Fig. 3, it is in order not make high pressure flow to control circuit via switch that K2 opens, so these switches can be by triode, relay, even diode is taken on, following example (as shown in Figure 5) is exactly to use diode D1, and D2 is used as K switch 1, and K2 uses, its objective is conduction period, do not make ac high-voltage enter control circuit at TRIAC.

The utility model can be generalized to adding in the thermal control of all heaters with ptc characteristics.

Claims

1. the circuit with bidirectional triode thyristor control MCH heater comprises: DC power-supply circuit, control circuit and alternating current; It is characterized in that also comprising: a bridge heap; Input two ends of described bridge heap are exported two ends with alternating current and are linked to each other; Heater and bidirectional triode thyristor serial connection back are at two ends of alternating current; One end of DC power-supply circuit links to each other with an output of bridge heap, and the other end of DC power-supply circuit links to each other with the control circuit vdd terminal, and control circuit GND end links to each other with another output of bridge heap; Between control circuit first output and The Trigger of Bidirectional Triode Thyristor end, also comprise one first switch; Sampling resistor and second switch serial connection back one end are connected in bidirectional triode thyristor and heater tie point, and the other end is connected in control circuit second output; Second switch links to each other with the control circuit input with the sampling resistor link.

2. the circuit with bidirectional triode thyristor control MCH heater according to claim 1, it is characterized in that: described first switch and second switch are triode or relay or diode.