KR0128228Y1 - Standard voltage control circuit for high frequency device - Google Patents

Abstract

The present invention relates to a reference voltage adjusting circuit of a high frequency heating apparatus. In the conventional high frequency heating apparatus, the output of the magnetron is always equal to the set value after comparing the average value of the current flowing through the magnetron with the output setting value at every cycle of the commercial power source. In this case, the output of the magnetron was also changed.

In order to solve this problem, the present invention compensates for the changed voltage value by using a multiplication circuit so that the output of the magnetron is always constant even if the commercial power is changed.

Description

Reference voltage control circuit of high frequency heating device

1 is a block diagram of a conventional high frequency heating device.

(A) to (d) of FIG. 2 are output waveform diagrams of the parts of FIG.

3 is a schematic diagram of a high frequency heating apparatus reference voltage adjusting circuit of the present invention.

(A) to (c) of FIG. 4 are output waveform diagrams of FIG.

* Explanation of symbols for main parts of the drawings

1: rectification / smoothing part 2: inverter part

3: high frequency generation unit 4: driving unit

5 synchronous detection unit 6 current detection unit

7: output setting unit 8: comparator

9 register increasing and decreasing unit 10 synchronizing signal generating unit

11: register 12: counter

13 clock generator 14 flip-flop

15: voltage compensator 16: voltage sampling part

17: multiplication unit

The present invention relates to a high frequency heating apparatus, and more particularly, to a reference voltage adjusting circuit of a high frequency heating apparatus that compensates for the changed voltage when the power supply voltage of the system is changed so that the output value of the magnetron heating the heated object is kept constant. will be.

FIG. 1 is a block diagram of a conventional high frequency heating apparatus, and as shown therein, rectification / smooth consisting of a bridge diode BD ₁ , a check coil CL ₁ , and a condenser C ₁ to rectify and smooth the commercial power source AC. The capacitor C ₂ and the diode D ₁ to turn on / off the driving signal of the driving unit 4 and the driving unit 4 to generate a high frequency voltage corresponding to the output signal of the rectifying / smoothing unit 1 on the secondary side. ), A capacitor (C ₃ ), a diode (D ₂ ), an inverter unit (2) consisting of a transistor (Q ₁ ), a transformer (T), and an oscillating high frequency signal by the output signal of the inverter unit ( ₂ ), A high frequency generator 3 composed of a magnetron MAG, a synchronous detector 5 for detecting a synchronous detection signal from an output signal of the inverter 2, and the magnetron MAG every cycle of a commercial power supply AC. A current detector 6 for detecting an average value of the current flowing through the output, an output setting unit 7 for setting an arbitrary output value, and the current A comparator 8 for comparing the output signal of the output section 6 and the output setting section 7 and the output signal of the comparator 8 in synchronization with the synchronous signal of the commercial power source output from the synchronous signal generator 10. Therefore, the register increasing / decreasing unit 9 for increasing or decreasing the count value set in the register 11 and the count value set in the register 11 are counted in reverse in synchronization with the clock signal output from the clock generator 13. A counter 12 and a flip-flop 14 which is set / reset in accordance with the output signals of the counter 12 and the synchronous detector 5 to control the driver 4.

The conventional high frequency heating device configured as described above is rectified by the bridge diode BD ₁ of the rectifying / smoothing part 1 after the commercial power source AC is smoothed by the condenser C ₁ , and thus, the transformer T of the inverter part 2. It is applied to the primary coil L ₁ . The inverter unit 2 generates a high frequency voltage to the transformer T secondary side coils L ₂ , L ₃ , and L ₄ by turning on and off the transistor Q _{1 in response} to a drive signal of the driving unit 4. When the high frequency voltage is rectified by the diode D ₂ of the high frequency generator 3 and applied to the magnetron MAG, the magnetron MAG oscillates the high frequency to heat the heated object.

At this time, if a signal such as (a) of FIG. 2 is generated in the secondary coil L ₄ of the transformer T by the resonant synchronization of the inverter unit 2, the synchronous detection unit 5 synchronizes with the signal. When a zero cross sync detection signal as shown in FIG. 2B is detected, and the flip-flop 14 is set at the falling edge of the sync detection signal, the driving unit 4 operates and the second unit is operated. As shown in FIG. 3D, the transistor Q ₁ of the inverter unit 2 is turned on.

On the other hand, from the high frequency voltage generated in the secondary coil L ₃ of the inverter unit 2, the current detector 6 detects the average value of the current flowing in the magnetron MAG at each cycle of the commercial power source AC, and compares the comparator ( When applied to the inverting terminal (-) of 8), the comparator 8 receives an output set value arbitrarily set by the output setting unit 7 as a non-inverting terminal (-), compares the average value with the set value, and generates a synchronization signal. The register increasing / decreasing unit 9 operating in synchronization with the commercial power source of the unit 10 detects the output signal of the comparator 8 and increases or decreases the count value of the register 11 by one step. If the average value is smaller than the set value of the output setting section 7, the step is increased. If the average value is larger than the set value, the value is decreased by one step. At this time, when the synchronous detection signal of the synchronous detection unit 5 is detected and reaches the falling edge as shown in (b) of FIG. 2, the count value of the register 11 is preset to the counter 12 and the counter ( 12 starts reverse counting the preset count value in synchronization with the clock signal output from the clock generator 13.

When the counter 12 completes the reverse count, when the completion signal is output as shown in (c) of FIG. 2, the flip-flop 14 is reset at the positive edge of the completion signal.

As a result, the driving unit 4 does not operate, and thus the transistor Q ₁ of the inverter unit 2 is turned off as shown in FIG.

At this time, the off time of the transistor Q ₁ is determined by the primary side coil L ₁ and the capacitor C ₁ of the inverter unit 2, and the inverter unit 2 is controlled by the synchronous detection signal of the synchronous detection unit 5. ) on the resonance synchronized with the transistor (Q ₁₎ of-synchronization is off is caught.

That is, if the average value of the current for heating the heated object is smaller than the set value, the count value of the resistor 11 is increased to increase the switching time of the transistor Q ₁ , thereby increasing the output of heating the heated object, and If the average value is larger than the set value, the count value of the resistor 11 is decreased to reduce the switching time of the transistor Q ₁ , thereby reducing the output of heating the heated object.

However, the conventional high frequency heating apparatus described above compares the current flowing through the magnetron with the randomly set output value at every cycle of the commercial power source, and then makes the current value flowing through the magnetron equal to the set value. There was a problem.

In order to solve this problem, the present invention devised a reference voltage adjusting circuit of a high frequency heating apparatus to compensate for the changed voltage when the commercial power is changed to maintain the output of the magnetron in detail, with reference to the accompanying drawings. The explanation is as follows.

3 is a block diagram of the reference voltage adjusting circuit of the high frequency heating apparatus of the present invention, and as shown in the drawing, it is composed of a bridge diode BD ₁ , a check coil CL ₁ , and a capacitor C ₁ to rectify a commercial power source AC. And a smooth rectification / smoothing unit 1, a capacitor C ₂ , a diode D ₁ , a transistor Q ₁ , and a transformer T, which are turned on and off in accordance with a driving signal of the driving unit 4. Inverter unit (2) for generating a high frequency voltage corresponding to the output signal of the rectification / smoothing unit (4) on the secondary side, and a capacitor (C3), diode (D ₂ ), magnetron (MAG) Periods of a high frequency generator 3 for oscillating high frequency by the output signal of (2), a synchronous detector 5 for detecting a synchronous detection signal from the output signal of the inverter 2, and a commercial power supply AC The current detection unit 6 for detecting the average value Iv of the current flowing through the magnetron MAG each time and the change in the commercial power source AC. A voltage compensator 15 for compensating the voltage by receiving the voltage output from the rectifying / smoothing part 1 and the output signal of the current detector 6, an output signal and an output setting part of the voltage compensator 15. A comparator 8 for comparing the output set values set in (7), a synchronization signal generator 10 for generating a synchronization signal of a commercial power supply, and an output signal of the synchronization signal generator 10 in synchronization with the comparator ( 8, the register increasing / decreasing unit 9 for increasing or decreasing the count value of the register 11 and the count value set in the resist 11 are inversely counted in synchronization with the clock signal of the clock generator 13; And a flip-flop 14 which is set / reset according to the output signals of the synchronous detection unit 5 and the counter 12 to drive the driving unit 4, and the voltage compensating unit ( 15 is a voltage sampling unit 16 for sampling the voltage output from the rectifying / smoothing unit (1), The multiplier unit 17 multiplies the output signal V ₁ of the voltage sampling unit 16 and the output signal Iv of the current detector 6.

When described in detail with reference to the accompanying drawings the effect of the present invention configured as described above.

The commercial power source AC is rectified by the bridge diode BD ₁ of the rectifying / smoothing unit 1 and then smoothed by the capacitor C ₁ to transformer T and the primary coil L _{1 of the} inverter unit 2. Is applied to the inverter unit 2 and the transistor Q ₁ is turned on and off by a drive signal of the driving unit 4 so that the transformer T and the secondary side coil L ₂ (L ₃ ) (L ₄ ) When the high frequency voltage is rectified by the diode D ₃ of the high frequency generator ₃ , smoothed by the capacitor C ₃ , and then applied to the magnetron MAG, the magnetron MAG ) Oscillates a high frequency to heat the heated object.

At this time, when a voltage corresponding to the primary coil L ₁ is generated in the secondary coil L ₄ of the transformer T by the resonant synchronization of the capacitor C _{2 of} the inverter unit 2, the synchronous detection unit 5 is performed. ) Detects a synchronous detection signal of zero cross from this signal, and the flip-flop 14 is set at the falling edge of the synchronous detection signal so that the driving unit 4 causes the transistor Q of the inverter unit 2 to operate. ₁ ) Turn on.

On the other hand, at the high frequency voltage generated in the secondary coil (L ₄ ) of the inverter unit 2, the current detector 6 detects the average value of the current flowing in the magnetron (MAG) every cycle of the commercial power supply voltage compensation unit 15 The output signal of the rectifying / smoothing section 1 is sampled by the voltage sampling section 16 of the voltage compensating section 15 and then outputted to the multiplication section 17 of the multiplier section 17. Is output to V ₁ .

Accordingly, the multiplier 17 multiplies the output V ₁ of the voltage sampling unit 16 by the output Iv of the current detector 6 to V ₁ × Iv to change the commercial power AC. Accordingly, the output of the magnetron MAG is compensated by the changed voltage such that the output of the magnetron MAG is equal to the set value P of the output setting unit 7 (V ₁ × Iv = p) and outputted to the comparator 8.

For example, if part A of Fig. 4 is an output waveform in a steady state, if the commercial power supply AC becomes large (assuming that the commercial power supply AC has a deviation of ± 15%), as shown in section B The output V ₁ of the voltage sampling unit 16 becomes large and the output Iv of the current detector 6 becomes small. At this time, the multiplier 17 multiplies the two output signals (V _{1 ×} Iv) to be equal to the set value P (V ₁ × Iv = P). As described above, when the output V ₁ of the voltage sampling unit 16 is lowered and the output Iv of the current detector 6 is higher, the two signals V ₁ are maintained such that the output of the magnetron MAG is kept constant. Multiply by Iv to compensate for the change in the commercial power source AC. Accordingly, the magnetron MAG heats the heated object to a constant output while the transistor Q ₁ is turned on.

Thereafter, when the comparator 8 compares the output V ₁ × Iv of the multiplier 17 with the set value P of the output setting unit 7, the resist increase / decrease unit 9 outputs the synchronization signal generator 10. In synchronization with the signal, the count value of the resist 11 is adjusted, and the counter 12 counter-counts the count value in synchronization with the clock signal output from the clock generator 13, and outputs a completion signal when the count is completed. The flip flop 14 is reset. Accordingly, the flip-flop 14 outputs a reset signal to stop driving of the driving unit 4 to turn off the transistor Q ₁ of the inverter unit 2.

As described above, the present invention compensates the voltage as much as the change of the commercial power even if the commercial power changes, so that the heating object can be heated at a constant magnetron output, and the power voltage fluctuates according to the regional change. There is an effect to compensate.

Claims (2)

The rectifier / smoothing unit 1 rectifies and smoothes the commercial power supply AC, and on / off according to the driving signal of the driving unit 4 to generate a high frequency voltage corresponding to the output signal of the rectifying / smoothing unit 1. An inverter unit 2, a high frequency generator 3 for oscillating high frequency in response to the output signal of the inverter unit 2, and a synchronous detection unit for detecting a synchronous detection signal from the output signal of the inverter unit 2; 5), a current detector 6 which detects an average value of the current flowing in the output signal of the inverter unit 2, and an output signal of the rectification / smoothing unit 1, after sampling the sampling value and the current detector Comparing the output signal of the voltage compensator 15 and the setting value of the output setting part 7 with the voltage compensator 15 which multiplies the output signal of (6) and compensates the voltage by the change of the commercial power source AC. The register 1 according to the output signal of the comparator 8 in synchronization with the output signal of the comparator 8 and the synchronization signal generator 10 A register increasing / decreasing unit 9 for increasing or decreasing the count value of 1), a counter 12 for inversely counting the count value set in the register 11 in synchronization with the clock signal of the clock generating unit 13, and the synchronous detecting unit (5) and a flip-flop (14) which is set / reset on the output signal of the counter (12) to drive the drive unit (4). 2. The voltage compensator of claim 1, wherein the voltage compensator 15 includes a voltage sampling part 16 for sampling the output signal of the rectifying / smoothing part 1, an output signal of the voltage sampling part 16, and the current detecting part (1). And a multiplier (17) for multiplying the output signal of (6).