JPH04106893U - High frequency heating device - Google Patents

Abstract

(57) [Summary] [Purpose] To enable self-diagnosis of inverter circuit failures using a microcomputer test mode without a measuring device. [Configuration] The anode current value flowing through the magnetron 12 is detected and converted into a digital value, and the digital value of the high frequency output setting value is transmitted to the microcomputer 13 through the communication circuit 15 and the communication circuit 14, When the computer is in an inspection mode, both digital values are compared and judged in a prescribed sequence, and when there is a difference between the two values by more than a prescribed value, an error is displayed on a display 18.

Description

[Detailed explanation of the idea]

0001

[Industrial application field]

This invention is a so-called inverter that drives a magnetron using an inverter circuit. The present invention relates to a high-frequency heating device equipped with a self-testing function for a motor drive circuit.

0002

[Conventional technology]

It rectifies the commercial AC power supply and sets it by the customer by turning the switching element on and off. This system is equipped with an inverter circuit that converts the high frequency output into AC power at a frequency corresponding to the high frequency output. In high-frequency heating equipment that supplies power to the magnetron using an inverter circuit. check whether the inverter circuit is operating normally at the set high frequency output. Conventionally, the method of checking is to measure the actual current and power values input to the inverter circuit. There was no choice but to measure it with a measuring device.

0003

[Problem that the idea aims to solve]

However, with this conventional example, ammeters and wattmeters for measuring current and power cannot be used. This is necessary and cannot be accomplished with simple tasks. Therefore, if there is no output at all This is not an extreme failure, but a failure where the high frequency output value differs from the set value. service personnel can easily measure this unless using the measuring instrument described above. I couldn't do it.

0004

[Means to solve the problem]

Easily test whether the inverter circuit is operating at the set high frequency output In order to do this, the anode current flowing through the magnetron is detected and converted into a digital value. This value is fed back to the microcomputer, and the microcomputer It is conceivable to compare the input value and the set value. Inverter type high frequency addition Thermal devices usually have multiple high-frequency output values that can be set, and a set value and a value for each of them. It is necessary to compare the input values and confirm that they are operating according to the set values. child In order to achieve this, the microcomputer is configured to perform this test in addition to its normal An inspection mode is provided to perform inspection, and the high frequency output is set according to the specified sequence. Change the values one after another, perform the above comparison from time to time, and check whether the input value is larger than the set value. If there is a significant difference, an error message will be displayed on the display.

[0005]

[Effect]

A current detection circuit detects the anode current flowing through the magnetron and converts it into a digital value. Convert and input the digital value to the microcomputer using the communication circuit and transmit it. do. An inspection mode that compares the set value and input value provided in the microcomputer. When the board is activated, it operates the inverter and also transmits the high frequency signal to the control circuit. The set value of the wave output is sequentially changed according to a prescribed sequence. At this time, each setting Read the input value at any given time, compare it with the set value, and determine the difference as specified. If it is greater than the value, it is assumed that there is an output difference and an error is displayed.

[0006]

【Example】

An embodiment of the present invention will be described below.

[0007] FIG. 1 is a circuit diagram showing an embodiment of the present invention.

[0008] The microcomputer 13 controls the operation of the inverter circuit for the control circuit 9. It outputs the start signal P to instruct stop, and also outputs the high frequency output setting value. It is output as a data signal SD1.

[0009] Data signal SD1 is 16-bit serial data, based on transmission start signal S1. It is transmitted in synchronization with clock signal CLK. This signal is input to the communication circuit 14. , here it is converted to 6-bit parallel data by shift register 14a etc. and is transmitted to the comparator 9a of the control circuit 9 as setting data PD1. On the other hand, Magne The current flowing through the tron 12 is detected by the current transformer 17, which converts the current into The signal is input to the detection circuit 16. Here, the rectified and smoothed voltage Vin is applied to the A/D converter. Therefore, it is converted to 6-bit parallel data PD2, which is controlled via the latch. It is fed back to the comparator 9a of the circuit 9 as input data. In comparison section 9a is this feedback input data PD2 and the microcomputer 13? and the setting data PD1 sent from the introduce. Based on this fed back comparison result, the pulse width controller 9b controls P Pulse width of pulse signal D that drives switching element 7 so that D1=PD2 control and adjust the output.

0010 The communication circuit 15 is an input that is fed back from the current detection circuit 16 to the control circuit 9. Take in data PD2 and send it to selector 15a, binary counter 15b, etc. Therefore, as shown in Figure 2, it is converted to 6-bit serial data SD2 and sent to the microcontroller. The fall of the transmission start signal S2 is determined using the clock signal CLK from the computer 13. The data is sent to the microcomputer 13 based on the reference value.

[0011] When the microcomputer 13 shifts to inspection mode, it turns on the start signal P. After that, change the setting data SD1 according to the sequence shown in Figure 3 to set the high frequency output. It sequentially outputs from 600W to 200W. Input data SD2 at each output Compare this with the setting data SD1 instructed to the control circuit 9, and find out the difference. If there are 8 or more codes, it is assumed that there is an output difference and the start signal P to the control circuit 9 is sent. Turn it off to stop the operation of the inverter circuit, and display an error message on the display 18. Show “E”.

0012 Input to the control circuit 9 may be caused by damage to parts of the inverter circuit or failure of the control circuit. The high frequency output may not be performed according to the set data, or the control circuit 9 may not match the set data. If the high frequency output value differs from the set value due to the data not being received correctly, This can be easily done by using the inspection mode of the microcomputer 13 mentioned above. can be diagnosed.

[0013]

[Effect of the idea]

As described above, according to the present invention, it is possible to make judgments without using conventional measuring instruments. Failure modes such as erroneous output that could not be detected can be easily detected, improving inspection efficiency. can be improved. In addition, as in the example, the control circuit is composed of a digital circuit. Therefore, it can be implemented at low cost by converting communication circuits etc. into LSI. It is possible to provide an excellent high-frequency heating device that has a self-diagnosis function for the inverter circuit.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram of an embodiment of the present invention.

FIG. 2 is a signal diagram of the communication section.

FIG. 3 similarly shows an inspection sequence.

[Explanation of symbols]

9 Control circuit 13 Microcomputer 14 Communication circuit 15 Communication circuit 16 Current detection circuit 18 Display

Claims (1)

[Scope of utility model registration request] [Claim 1] A rectifier and smoothing circuit that rectifies and smoothes a commercial power supply to produce a DC power supply, a transformer, a capacitor, a diode,
an inverter circuit composed of switching elements;
A control circuit that controls on/off switching elements of the inverter circuit, a magnetron driven by a high frequency power source generated by the inverter circuit, a microcomputer that controls the operation of the control circuit, and a microcomputer that controls the operation of the control circuit. a communication circuit that transmits a high-frequency output setting digital value from the microcomputer; a current detection circuit that detects the anode current value of the magnetron, converts it into a digital value, and transmits it to the control circuit; A display device that lights up is provided with a second communication circuit that transmits the digital value converted by the current detection circuit to the microcomputer as an input value, and a A test mode for processing input is provided in the microcomputer, and in this test mode, the microcomputer sequentially changes the digital output value outputted to the control circuit through the communication circuit according to a prescribed sequence, and A high-frequency heating device characterized in that if the difference between the input value and the input value that is input from time to time is equal to or greater than a specified value, it is determined to be abnormal and an error is displayed on the display.