CN1288129A

CN1288129A - High precision programmed energy saving electro magnetic furnace

Info

Publication number: CN1288129A
Application number: CN 99118236
Authority: CN
Inventors: 陈惠强
Original assignee: Individual
Current assignee: Individual
Priority date: 1999-09-09
Filing date: 1999-09-09
Publication date: 2001-03-21

Abstract

An energy-saving program-controlled electromagnetic stove is composed of shell, primary circuit board and CPU circuit module, and features that its protecting circuit is composed of sampling hardware and rectifying trigger and controlled by CPU module. Its advantages include high stability and reliability, long service life, and high thermal efficiency.

Description

High precision programmed energy saving electro magnetic furnace

The present invention relates to design of electromagnetic oven shell mechanism and internal circuit Module Design and improve particularly a kind of high precision programmed energy saving electro magnetic furnace.

Electromagnetic oven is since coming out, a lot of countries have in the world obtained developing rapidly, especially developed country, popularity rate is very high, yet, the electromagnetic oven of Xiao Shouing in the market, in varying degrees parts that come with some shortcomings: mainly be owing to lack the scientific and reasonable structural design and the modular design of control circuit more, cause internal circuit element to interfere with each other and cause temperature rise too high, thereby influence the stability of governor circuit work, shortened the service life of electromagnetic oven, add the rational circuit module design of shortage, heat energy loss is bigger when causing electromagnetic oven work, does not therefore fully effectively utilize high this advantage of its thermal efficiency, cost is also corresponding higher, has also caused certain difficulty for the popularization in market.

The objective of the invention is at above-mentioned shortcoming, the internal circuit module of electromagnetic oven and the design of shell mechanism are improved, thereby make electromagnetic oven that breakthrough progress arranged: have good operating stability, long service life, thermal efficiency height, low cost and other advantages.

The object of the present invention is achieved like this:

One, improves the shell mechanism design of electromagnetic oven and the circuit board components and parts arrangement position that is heated, make its result of ventilating heat dissipation more reasonable, simultaneously owing to covered out electric field, the interference in magnetic field and the influence of heater coil high temperature, strengthened the equiva lent impedance of the main components and parts of internal circuit, thereby make the more stable work of electromagnetic oven, longer service life.

Two, improve the internal circuit design of electromagnetic oven, principle according to electromagnetic induction, at first produced the pulse wave signal of a preset width by central control circuit (oscillating circuit), its amplitude changes along with the voltage swing of the resonance circuit of L (heater coil) and C (resonant capacitance) formation.Now the A/D mouth of this signal by CPU (circuit module) sent instruction to it; calculate the duty ratio of each cycle P pulse wave output again by CPU; be consistent with the signal that comes synchronously; the switching frequency of high power transistor (IGBT or FET) and the resonant frequency of the LC resonant tank that L (heater coil) C (resonant capacitance) constitutes are consistent; this moment is by L; the both end voltage of the resonant tank that C constitutes is in maximum rating; the loss of high power transistor is also just more little; thereby make the temperature rise of high power transistor under the inductive load state reduce to minimum; it is excessive because of loss thoroughly to have eliminated high power transistor (IGBT or FET); cause the quick heating of moment wafer and very easily impaired problem; it is big also to have solved the electric current change when heated condition of traditional electromagnetic oven; produce self-excitation; from this problem of damage; more improved simultaneously the thermal efficiency of electromagnetic oven; make electromagnetic oven work more stable; longer service life; owing to adopt the cpu circuit modular design; therefore some traditional holding circuits are changed to directly and are controlled by CPU; reduce production cost, played very big effect also for the popularization in market.

Accompanying drawing 1 is an external structure schematic diagram of the present invention, and accompanying drawing 2 is internal structure and element Bututs of shell of the present invention, and accompanying drawing 3 is internal circuit configuration block diagrams of the present invention.

In conjunction with the accompanying drawings and embodiments, further describe external structure of the present invention and internal circuit configuration.

See also shown in Figure 1ly, the shell of electromagnetic oven installs power switch button [1], goes up trim button [2], trim button [3], top button [4], insulation button [5], power supply indicator [6], insulation indicator lamp [7], indicator lamp [8], power indicator lamp [9], [10], [11], [12], [13], [14], [15], [16] fast down.

Plug in, press power switch button [1], power supply indicator [6] is promptly lighted, at this moment, electromagnetic oven waits for that the user selects working method, and the user can select different working methods according to actual needs, as: the Fast Heating function, heat insulation function, if select to go up trim button [2], trim button [3] down, can circulate and regulate the power of electromagnetic oven, can divide little, weak, in, strong fourth gear, advantage of the present invention is: easy to operate, nimbly and freely.

See also shown in Figure 2, the air port is left in shell (drain pan) both sides [18] at electromagnetic oven, purpose is to be convenient to circulation of air, make its ventilation and heat more reasonable, [26] be the circuit board of electromagnetic oven, [19] be resonant capacitance, [20] be smoothing capacity, [21] be choke coil, [22] be filter capacitor, [23] be filter inductance, [24] be filter capacitor, [25] be power transformer, above main heater element is distributed to ventilating opening, purpose is to be convenient to heat radiation, the more important thing is: electromagnetic oven in the course of the work, if above main element is not covered the interference of open field line, when electric field and magnetic field act on the contiguous element so, will make and produce undesirable electric current and voltage on these elements, and electric current that produces in these contiguous elements and the conductor and voltage can influence original circuit and electric current in the element and voltage by reverse impact, thereby finally cause the change of the equiva lent impedance of element, cause the electromagnetic oven circuit unstable working condition, when serious even directly destroy the operate as normal of electromagnetic oven.Owing to adopted the present invention, the main components and parts of electromagnetic oven major loop plate have covered out electric field, the interference in magnetic field and the temperatures involved of heater coil, thereby make the workpiece of electromagnetic oven stable more, reliable, longer service life.

Please continue to consult accompanying drawing 3; the present invention is by detecting at: [27] zero point; [28] electric source filter circuit; [29] drive circuit; [30] high-frequency filter circuit; [31] power oscillating circuit; [32] central control circuit (oscillating circuit); [33] synchronous follow-up circuit; [34] civil power is crossed low too high protection sample circuit; [35] pulse protection sample circuit; [36] thermostatic control sample circuit; [37] transistor overtemperature protection sample circuit; [38] high voltage protective sample circuit; [39] current sampling circuit; [40] supply voltage sample circuit; [41] wrong detection; [42] DISPLAY (display circuit); [43] the cpu circuit module is interconnected to constitute.Now do further to describe according to the annexation between foregoing circuit: electromagnetic oven is in gastronomical process; because load changes through regular meeting; its circuit just can be in the different operating state thereupon; safety in order to ensure power tube; it is carried out under no impact conditions; after the power supply of electromagnetic oven is switched on; cpu circuit module of the present invention [43] utilizes the comparator of central control circuit [32] to export a negative pulse by detection at zero point [27] and wrong detection [42] at supply voltage near zero point; utilize pulse control electromagnetic oven driving pulse zero-time; spare at supply voltage place at zero point when guaranteeing and carry out with start; automatically discern self check through CPU again; whether the pulse wave signal of scanning probe central control circuit (oscillating circuit) [32] regularly sends simultaneously; and it is synchronous with synchronous follow-up circuit [34] maintenance; power tube turns to duty with cut-off state; must carry out at power supply 50Hz voltage zero-cross place, just enter original state then, CPU waits for that the user selects working method.

Central control circuit of the present invention [32], be the pulse oscillator of a frequency of commonly using at 20～45KHz, it produces the pulse wave signal of preset width by vibration and is consistent with synchronous follow-up circuit, through drive circuit [29] signal is amplified, connect high-frequency filter circuit [30] again its filtration is added to power transistor (IGBT or FET), make its conducting.The continuous change action of the ON/OFF of power transistor makes the L (heater coil) of power oscillating circuit [31] produce high-frequency alternating magnetic field, comes the induction cookware heating, thereby reaches the purpose of cooking.

Main holding circuit within the present invention; it mainly is to be finished by five A/D mouths of cpu circuit module [43]; when power oscillating circuit [31] operation; when entering the higher-order of oscillation; civil power is crossed low too high protection sample circuit [34]; pulse protection sample circuit [35]; thermostatic control sample circuit [36]; transistor overtemperature protection sample circuit [37]; high voltage protective sample circuit [38] is directly sampled to it; then the data of sampling are directly notified cpu circuit module [43] by the A/D mouth; the cpu circuit module limits pulse bandwidth according to the data that read by automatic detection of predefined program.Finish scanning in the short period of time, discern, change this process, and then detect the pulse wave signal of next cycle, restPose, electromagnetic oven continues operate as normal.Five groups of sample circuits of the present invention are one group of detection trigger in fact, also can adopt identification circuit commonly used through Capacitance Coupled and electric resistance partial pressure recomposition wave detector simultaneously, play the effect of amplitude limit, thereby reach the purpose of protection.

Cpu circuit module of the present invention [43], it utilizes the rule of the pulse bandwidth of central control circuit (oscillating circuit) [32] generation and the resonance circuit voltage swing variation that LC constitutes, directly central control circuit is sampled, the duty ratio of calculating the output of each cycle PWM pulse wave by CPU is consistent with the signal that synchronous follow-up circuit [33] comes again, and the resonant frequency of the LC resonant tank of the switching frequency of high power transistor (IGBT or FET) and L (heater coil) C (resonant capacitance) formation is consistent.At this moment, the voltage that is made of the resonant tank two ends L, C is in maximum rating, and the loss of high power transistor is also just more little, makes high-frequency oscillating circuits at one's best, thereby improves the thermal efficiency.Owing to adopted the present invention, thereby make the temperature rise of high power transistor under the inductive load state reduce to minimum, it is excessive because of loss thoroughly to have eliminated high power transistor (IGBT or FET), cause the quick heating of wink portion's wafer and very easily impaired problem, it is big also to have solved the electric current change when heated condition of traditional electromagnetic oven, produce self-excitation, decrease this problem certainly, make the more stable work of electromagnetic oven, longer service life.Owing to adopted the present invention, therefore traditional peripheral hardware holding circuit directly by CPU control, has reduced production cost significantly, has played very big impetus for the popularization in market.

Claims

1, the high precision programmed energy saving electro magnetic furnace of being made up of shell and inner major loop plate, cpu circuit module is characterized in that: the shell of electromagnetic oven is installed power switch button [1], last trim button [2], following trim button [3], top button [4], insulation button [5], power supply indicator [6], insulation indicator lamp [7], indicator lamp [8] fast, power indicator lamp [9], [10], [11], [12], [13], [14], [15], [16].

2, high precision programmed energy saving electro magnetic furnace according to claim 1, it is characterized in that: the shell of electromagnetic oven (drain pan) both sides [18] have air outlet, the main heater element of major loop plate [26] is distributed to ventilating opening, be convenient to ventilation and heat, strengthen the equiva lent impedance of the main components and parts of internal circuit simultaneously, we opens the interference in electric field magnetic field, makes the more stable work, reliable of electromagnetic oven.

3, high precision programmed energy saving electro magnetic furnace according to claim 1, it is characterized in that: the control of the switching frequency of high power transistor (IGBT or FET) is to be controlled by the cpu circuit module, central control circuit (oscillating circuit) [32] directly sends instruction by the A/D mouth to cpu circuit module [43], and be consistent with the signal of synchronous follow-up circuit [33], thereby the resonant frequency in transistorized switching frequency and LC loop is consistent, make the voltage at oscillating circuit two ends be in maximum rating, therefore the power tube loss is more little, it is excessive because of loss thoroughly to eliminate high power transistor (IGBT or FET), cause wafer quick heating of moment and impaired problem, also improved the thermal efficiency of electromagnetic oven simultaneously.

4, high precision programmed energy saving electro magnetic furnace according to claim 1; it is characterized in that: all holding circuits are directly by the cpu circuit module controls; wherein be provided with one group of detection trigger; this detection trigger plays amplitude limit; follow the trail of circuit and guarantee the unlikely generation overload situations of total system, thereby reach protective effect.