KR100891658B1 - Method for Sensing Condition of Inverter Module In The Microwave Oven - Google Patents

Abstract

The present invention relates to a method for detecting an inverter module state of a microwave oven capable of detecting a state of an inverter module in a microwave oven and providing a detailed breakdown to the user. The present invention relates to a method for outputting a PWM control signal and outputting a pulse counter, a high counter, and a low counter. In the inverter module state detection method of the microwave oven comprising a microcomputer having a microcontroller and an inverter module for controlling the driving of the magnetron according to the PWM control signal of the microcomputer and outputting a feedback signal according to the driving of the magnetron, the feedback input from the inverter module Checking a signal and displaying an error message corresponding to 'oscillation abnormality' if the feedback signal is not input during a preset startup time at initial startup; Displaying an error message corresponding to an 'internal defect' when a feedback signal that maintains a high state for a predetermined time or more during the oscillation after the set start time or after the set start time has elapsed; Displaying an error message corresponding to 'internal element damage' when a feedback signal that maintains a low state for a predetermined time or more during an oscillation after the set startup time elapses; In addition, when the feedback signal in the low state is input in the stop mode, an error message corresponding to 'current leakage' is displayed. Therefore, the abnormal state of the inverter module can be accurately identified and a detailed failure history can be provided to the user. The reliability can be further improved.

Inverter module / error status

Description

Method for Sensing Condition of Inverter Module in Microwave Oven

1 is a block diagram showing the configuration of a typical microwave oven

2 is a flowchart illustrating a method of checking a feedback signal of an inverter module in the present invention.

3 is a waveform diagram showing a PWM signal and a feedback signal

4 is a waveform diagram showing a feedback signal and a sampling signal;

5 is a flowchart illustrating a method for detecting an inverter module state of a microwave oven according to the present invention.

6A to 6E are waveform diagrams of feedback signals showing different abnormal states of the inverter module.

Explanation of symbols for main parts of the drawings

1: magnetron 2: inverter module

3: micom

The present invention relates to a microwave oven, and more particularly, to a method for detecting an inverter module state of a microwave oven to detect a state of an inverter module in a microwave oven and provide a detailed breakdown to a user.

Recently, as a home appliance for cooking at home, a gas range, a gas oven, a microwave oven, an electric oven and the like have been widely used.

Here, the microwave oven is a device that heats / cooks a cooking object in a cavity by using microwave as a main heating source, and includes a high voltage transformer, a magnetron, and the like. This high-voltage transformer generates a predetermined high voltage to drive the magnetron, which emits microwaves of high frequency (approximately 2450 MHz) in an enclosed space in which food is stored.

The microwaves emitted from the magnetron vibrate the water molecules contained in the food, and molecular friction heat is generated by the vibrations of the water molecules to heat / cook the food.

Typically, such a microwave oven uses an inverter method to control the driving of the magnetron.

Referring to FIG. 1, a microwave inverter of a general inverter system will be described. In a microwave oven having a power input unit (not shown), a magnetron 1 for generating a microwave and a set voltage corresponding to a user's request are described. In accordance with the microcomputer 3 for outputting a PWM (Pulse Width Modulation) control signal, and an inverter module for generating a PWM signal based on the PWM control signal output from the microcomputer 3 to control the driving of the magnetron (1) It consists of (2).

In the microwave oven according to the related art configured as described above, the microcomputer 3 first outputs a driving signal to the inverter module 2 according to a user's request, and also outputs a PWM control signal according to a user's set voltage.

The inverter module 2 receives AC power through the power input unit, boosts and amplifies the AC power, outputs a PWM signal based on the PWM control signal output from the microcomputer 3, and outputs the PWM signal according to the PWM signal. The amplified voltage is supplied to the magnetron 1.

The magnetron 1 receives the voltage supplied from the inverter module 2 according to the PWM signal and generates a microwave as a main heating source.

In this case, the inverter module 2 drives the magnetron 1 according to the PWM signal and outputs a corresponding feedback signal to the microcomputer 3.

In general, the signal fed back from the inverter module 2 is inputted to the microcomputer 3 by outputting one cycle 1T per two cycles 2T of the PWM signal output from the microcomputer 3.

In the conventional case, the microcomputer 3 recognizes that the inverter module 2 is in an abnormal state when the signal fed back from the inverter module 2 does not output one cycle per two cycles of the PWM signal, and displays it (not shown). ) Is displayed.

The above-mentioned conventional inverter type microwave oven only displays one error mode because it indicates an error state when there is no feedback signal of one cycle per two cycles of the PWM signal, and it is possible to determine whether the inverter module has a cause of failure. There was no.

That is, it is difficult to accurately determine the cause of the abnormal state that occurs during abnormal operation of the inverter module has a problem that it is difficult to determine the exact state of the inverter module.

Accordingly, the present invention has been made to solve the above-described problems according to the prior art, an object of the present invention is to detect the state of the inverter module in the microwave oven to provide a detailed breakdown history to the user of the microwave oven It is to provide a module state detection method.

In order to achieve the above object, an inverter module state sensing method of a microwave oven according to the present invention outputs a PWM control signal and includes a microcomputer having a pulse counter, a high counter and a low counter, and a magnetron according to the PWM control signal of the microcomputer. In the inverter module state detection method of the microwave oven comprising an inverter module for controlling the control and outputting a feedback signal according to the magnetron driving, the feedback signal is input during the initial startup time by checking the feedback signal input from the inverter module Displaying an error message corresponding to 'oscillation abnormality' if it is not input; Displaying an error message corresponding to an 'internal defect' when a feedback signal that maintains a high state for a predetermined time or more during the oscillation after the set start time or after the set start time has elapsed; Displaying an error message corresponding to 'internal element damage' when a feedback signal that maintains a low state for a predetermined time or more during an oscillation after the set startup time elapses; In addition, if a feedback signal of a low state is input in the stop mode, the method may include displaying an error message corresponding to 'current leakage'.

In this case, the method of checking the feedback signal input from the inverter module periodically outputs a sampling signal, and stores the previous state of the input feedback signal and if the current input feedback signal is a high state, Accumulating an output period at the high counter; and if the accumulated value of the high counter has passed a preset time and the previous state of the feedback signal is low, increasing the pulse counter and initializing the low counter. And accumulating the output period of the sampling signal in the low counter when the input feedback signal is in a low state, and a cumulative value of the low counter has passed a predetermined time and is in a previous state of the feedback signal. If was high, increase the pulse counter and initialize the high counter. It is characterized by consisting of steps.

Other objects, features and advantages of the present invention will become apparent from the following detailed description of embodiments taken in conjunction with the accompanying drawings.

Referring to the accompanying drawings, the inverter module state detection method of the microwave oven according to the present invention will be described.

2 is a flow chart illustrating a method of checking a feedback signal of an inverter module in the present invention, FIG. 3 is a waveform diagram illustrating a PWM signal and a feedback signal, and FIG. 4 is a waveform diagram illustrating a sampling relationship of a feedback signal. 5 is a flowchart illustrating a method for detecting an inverter module state of a microwave oven according to the present invention, and FIGS. 6A to 6E are waveform diagrams of feedback signals representing different abnormal states of the inverter module.

First, the microwave oven according to the present invention is similar in configuration to the above-described prior art, and the same reference numerals are used for the same configuration, but in the microwave oven according to the present invention, the microcomputer 3 drives the magnetron 1 according to the drive. A pulse counter (not shown) for counting the number of times every 1/2 cycle of the feedback signal input from the module 2, and a high counter for counting a sampling signal for sampling the high state of the feedback signal ( High Counter (not shown) and a Low Counter (not shown) for counting a sampling signal for sampling a low state of the feedback signal. By grasping the state in detail, it is characterized in displaying the abnormal state of the inverter module 2 to the user more accurately.

Hereinafter, a method of checking a feedback signal input from the inverter module 2 will be described in detail.

As shown in FIG. 2, first, a sampling signal for sampling the feedback signal input from the inverter module 2 is output every 500 ms (S00).

At this time, the inverter module 2 outputs a feedback signal of 1/2 cycle (4.7 ms) for every one cycle (4.7 ms) of the PWM control signal input from the microcomputer 3 as shown in FIG.

As shown in FIG. 4, the microcomputer 3 outputs eight sampling signals every 500 ms during 4.0 ms for sampling of the feedback signal at 1/2 cycle (4.7 ms).

Subsequently, the previous state of the input feedback signal is stored and it is determined whether the pulse of the currently input feedback signal is high (S10).

As a result of the determination (S10), when the pulse of the feedback signal currently input is in a high state, 500 ms periods are accumulated in the high counter for each output sampling signal (S11).

In addition, it is determined whether the cumulative value of the high counter has passed 4.0 ms, and whether the previous state of the feedback signal is low, that is, whether the current feedback signal is a feedback signal transitioned from a low state to a high state. (S12-S13).

As a result of the determination (S12 to S13), if the cumulative value of the high counter has passed 4.0 ms and the previous state of the feedback signal is low, the pulse counter is increased by 1 and the low counter is initialized (S14 to S15). .

On the other hand, if the pulse of the feedback signal currently input, the determination result (S10) is low state, 500ms period is accumulated in the low counter for each output sampling signal (S20).

Then, it is determined whether the cumulative value of the low counter has passed 4.0 ms, and whether the previous state of the feedback signal is high, that is, whether the current feedback signal is a feedback signal transitioned from a high state to a low state. (S21-S22).

As a result of the determination (S21 to S22), if the cumulative value of the low counter has passed 4.0 ms and the previous state of the feedback signal is high, the pulse counter is increased by 1 and the high counter is initialized (S23 to S24). .

By continuously repeating the checking process of the above-described feedback signal, the state of the feedback signal input from the inverter module 2 can be continuously checked.

The inverter module state detection method of the microwave oven according to the present invention is possible by continuously identifying the state of the feedback signal through the above-described process.

Therefore, the state detection method of the inverter module according to the present invention will be described in detail with reference to FIG.

First, it is determined whether the current inverter module 2 is in an initial startup state (S50).

In general, the microcomputer 3 outputs an initial start signal for about 7 seconds in the PWM control signal to drive the magnetron 1 according to a user's request.

As a result of the determination (S50), if it is the initial start entry state, it is determined whether the start setting time 7 seconds has elapsed (S51), and when the start setting time 7 seconds has elapsed, it is determined whether the accumulated value of the pulse counter is 0 (S52). ).

As a result of the determination (S52), even after 7 seconds have elapsed after the start signal is output, if the accumulated value of the pulse counter has a value of 0, it is determined as an abnormal state due to an oscillation abnormality and an error message corresponding to "oscillation abnormality" is displayed ( S53).

That is, as shown in FIG. 6A, the PWM control signal is input, but the feedback signal maintains the low state a is determined to be an abnormal state in which power is supplied to the inverter module 2 but oscillation is not performed.                     

At this time, the microcomputer 3 senses such an abnormal state and outputs a stop signal (a PWM control signal in a low state) to stop driving the system and display an error message (eg, H98) indicating "oscillation abnormality". .

Here, in the normal case, when the PWM control signal is low, that is, when the stop signal, the feedback signal maintains a high state.

On the other hand, if the cumulative value of the pulse counter is not 0, that is, the oscillation is made, the determination result 52 determines whether or not the cumulative value of the high counter is 200 Hz or more (S60).

As a result of the determination (S60), if the accumulated value of the high counter is 200 ms or more, that is, as shown in FIG. 6B, the feedback signal generates a high state (b) of 200 ms or more during the oscillation duration after 7 seconds of the start setting time. If it is maintained, it is recognized as an abnormal state due to an internal defect of the inverter module 2 due to an overload or the like during operation, and displays an error message (eg, H97) corresponding thereto (S61).

As a result of the determination (S60), if the cumulative value of the high counter is not more than 200 ms, it is determined whether the cumulative value of the low counter is 200 ms or more (S70).

At this time, if the cumulative value of the low counter is 200 ms or more, that is, as shown in FIG. 6C, the feedback signal is 200 ms or more in the oscillation duration after 7 seconds of the start setting time, as shown in FIG. 6C. ) Is recognized as an abnormal state caused by damage to an internal device such as a current device or a switching device during driving, and displays an error message (eg, H96) corresponding thereto (S71).                     

In addition, if the determination result (S51), the start setting time has not passed 7 seconds, it is determined whether the cumulative value of the pulse counter is greater than or equal to the predetermined value (approximately, 6) (S72).

As a result of the determination (S72), if the cumulative value of the pulse counter does not pass a predetermined value, it is determined whether the cumulative value of the current high counter is 200 ms or more (S73), and the cumulative value of the high counter is 200 ms or more. In other words, if the feedback signal maintains the high state (d) of 200 Hz or more in a state in which the start setting time has not elapsed, as shown in FIG. 6D, the internal controller of the inverter is forcibly stopped due to an internal fault of the inverter and corresponding thereto. An error message H97 is displayed (S61).

Then, in the determination result (S50), if the stop mode entry state other than the initial start entry state, it is determined whether the accumulated value of the current low counter is 5 ms or more (S80 to S81).

As a result of the determination (S81), if the cumulative value of the low counter is 5 ms or more in the stop mode state, that is, as shown in FIG. If it is maintained, it is recognized that current leakage occurs in the inverter module 2 and displays an error message (eg, H99) corresponding thereto (S82).

Therefore, the present invention can more accurately recognize the detailed abnormal state of the inverter module by continuously identifying the state of the feedback signal using the pulse counter, the high counter and the low counter. In addition, by displaying the corresponding error message according to various abnormal conditions, the user can accurately identify the failure point of the microwave oven.

Inverter module state detection method of the microwave oven according to the present invention described above by using the pulse counter, high counter and low counter to continuously grasp the state of the feedback signal to determine the abnormal state of the inverter module more accurate and detailed failure history It can provide to the user has the effect of improving the reliability of the system more.

Those skilled in the art will appreciate that various changes and modifications can be made without departing from the spirit of the present invention.

Therefore, the technical scope of the present invention should not be limited to the contents described in the embodiments, but should be defined by the claims.

Claims (3)

Inverter of the microwave oven consisting of a microcomputer with a PWM control signal, a pulse counter, a high counter and a low counter, and an inverter module that controls the driving of the magnetron according to the PWM control signal of the microcomputer and outputs a feedback signal according to the magnetron driving. In the module state detection method, Checking an feedback signal input from the inverter module and displaying an error message corresponding to an 'oscillation error' if the feedback signal is not input during a preset startup time at initial startup; Displaying an error message corresponding to an 'internal defect' when a feedback signal that maintains a high state for a predetermined time or more during the oscillation after the set start time or after the set start time has elapsed; Displaying an error message corresponding to 'internal element damage' when a feedback signal that maintains a low state for a predetermined time or more during an oscillation after the set startup time elapses; And, And displaying an error message corresponding to 'current leakage' when a feedback signal of a low state is input in the stop mode. The method of claim 1, The check method of the feedback signal input from the inverter module Periodically outputting a sampling signal, Storing the previous state of the input feedback signal and accumulating the output period of the sampling signal in the high counter when the current input feedback signal is high; Incrementing the pulse counter and initializing the low counter when the accumulated value of the high counter has passed a preset time and the previous state of the feedback signal is low; Accumulating the output period of the sampling signal in the low counter when the input feedback signal is in a low state; And increasing the pulse counter and initializing the high counter when the cumulative value of the low counter has passed a preset time and the previous state of the feedback signal is high. . The method of claim 2, The set time is Inverter module state detection method of a microwave oven, characterized in that less than a half cycle of the feedback signal.

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