阅读说明：本技术 一种磁控管电源测控方法 (Magnetron power supply measurement and control method ) 是由 马中发 齐晓智 孙占赢 汤红花 于 2019-09-18 设计创作，主要内容包括：本发明涉及磁控管电源技术领域,具体属于一种磁控管电源测控方法,包括整流滤波单元,驱动控制单元,采样电路单元,功率调节单元和信号处理控制单元,整流滤波单元将交流输入电压整流滤波后向主功率回路供电,驱动控制单元通过驱动IC控制功率开关管通断,采样电路单元获取功率输出回路中电流大小,功率调节单元通过接收微处理器的PWM信号来调节输出功率,信号处理控制单元通过微控制器读取所述采样电路单元输出回路电流大小,改变输出PWM波占空比。本发明能够控制磁控管电源系统的输出电流,延长磁控管使用寿命,还可实时监控电源输出电流,若电源输出电流异常可关断功率输出,避免电源损坏。(The invention relates to the technical field of magnetron power supplies, in particular to a magnetron power supply measurement and control method, which comprises a rectification filtering unit, a driving control unit, a sampling circuit unit, a power regulation unit and a signal processing control unit, wherein the rectification filtering unit rectifies and filters alternating-current input voltage and then supplies power to a main power loop, the driving control unit controls the on-off of a power switch tube through a driving IC, the sampling circuit unit acquires the current in a power output loop, the power regulation unit regulates the output power by receiving a PWM (pulse width modulation) signal of a microprocessor, and the signal processing control unit reads the current of the output loop of the sampling circuit unit through a microcontroller to change the duty ratio of an output PWM wave. The invention can control the output current of the magnetron power supply system, prolong the service life of the magnetron, monitor the output current of the power supply in real time, and turn off the power output if the output current of the power supply is abnormal, thereby avoiding the damage of the power supply.)

1. A magnetron power supply measurement and control method is characterized in that: the power supply device comprises a rectification filtering unit, a driving control unit, a sampling circuit unit, a power regulating unit and a signal processing control unit, wherein the rectification filtering unit supplies power to a main power loop after rectifying and filtering alternating-current input voltage, the driving control unit controls the power switch tube to be switched on and off through a drive IC (integrated circuit), the sampling circuit unit obtains the current size in the power output loop, the power regulating unit regulates the output power through a PWM (pulse width modulation) signal of a receiving microprocessor, and the signal processing control unit reads the current size of the output loop of the sampling circuit unit through a microcontroller to change the duty ratio of output PWM waves.

2. The magnetron power supply measurement and control method according to claim 1, characterized in that: the signal processing unit comprises the following steps:

(1) monitoring output current (I) in real time during power supply operation_out）；

(2) Setting an output current reference value (I)_set）；

(3) Setting a maximum error value (I) of the allowable output current_△）；

(4) Setting the output maximum current value (I)_max）；

(5) Setting output minimum current value (I)_min）；

(6) After starting up, the output current (I) is enabled_out) Slowly increasing;

(7) dynamically adjusting output current value (I)_out) Size;

(8) detecting an open circuit of an output current loop;

(9) detecting short circuit of an output current loop;

(10) and monitoring the temperature of the output power chip.

3. The magnetron power supply measurement and control method according to claim 2, characterized in that: when the power supply is started, the PWM duty ratio is gradually increased to a certain proportion and then is kept unchanged, the magnetron filament is preheated, and the PWM duty ratio is continuously increased after 2 seconds until I_outIs close to I_set。

4. The magnetron power supply measurement and control method as claimed in claim 2, wherein: when the said I_out < I_set-at I Δ, increasing the PWM duty cycle; when the said I_out > I_setWhen + I delta, reducing the PWM duty ratio; when the said I_set+I△< I_out < I_set-I Δ, the output PWM duty cycle is maintained constant.

5. The magnetron power supply measurement and control method according to claim 2, characterized in that: when the said I_out > I_maxWhen the power supply is short-circuited, the power supply enters a protection mode.

6. The magnetron power supply measurement and control method as claimed in claim 2, wherein: when the said I_out < I_minWhen the power supply is open, the power supply enters a protection mode.

7. The magnetron power supply measurement and control method according to claim 2, characterized in that: when the temperature on the power chip exceeds 70 ℃, the output power of the power supply starts to be reduced; when the temperature on the power chip exceeds 85 ℃, the power supply heat dissipation system is considered to be in fault, at the moment, the power output is closed, and the power supply enters a protection mode.

Technical Field

The invention relates to the technical field of magnetron power supplies, in particular to a magnetron power supply measurement and control method.

Background

Magnetrons and klystrons are currently the main devices used in industrial applications, particularly in the field of microwave heating. The energy feeding structure, the waveguide element, the applicator, the sensor and the controller, the microwave power source and the like form a microwave power device, wherein the microwave power source is used for generating microwaves, which is the most important component in the whole microwave power device. The performance of the microwave power equipment depends on the quality of the performance of the microwave power source, so that the improvement of the production technology of the microwave power source has important significance for improving the performance of the microwave power equipment. The driving power supply of the magnetron in the microwave power source directly determines the performance of the microwave power source. The traditional microwave magnetron power supply is mostly a power frequency boosting power supply, a power frequency transformer is adopted to boost voltage to obtain high-voltage electric energy to supply power for the magnetron, the power supply is large in size, low in efficiency and large in switching noise, the pollution to a power grid is serious, the output voltage of the traditional magnetron power supply is not adjustable, the power can be adjusted only by changing the intermittent working time of the power supply, and the service life of the magnetron can be influenced by the adopted intermittent power supply mode.

The purpose of this patent lies in providing a magnetron power supply observes and controls method, makes the output current of magnetron power supply in the start-up process slowly increase, prolongs magnetron life, still can real time monitoring power output current, if power output current is unusual, the controller promptly gets into the protection mode and shuts off power output, avoids the power to damage.

Disclosure of Invention

In order to achieve the purpose, the invention provides the following technical scheme:

a magnetron power supply measurement and control method comprises a rectification filter unit, a drive control unit, a sampling circuit unit, a power regulation unit and a signal processing control unit, wherein the rectification filter unit rectifies and filters alternating-current input voltage and then supplies power to a main power loop, the drive control unit controls the power switch tube to be switched on and off through a drive IC (integrated circuit), the sampling circuit unit acquires the current in the power output loop, the power regulation unit regulates the output power by receiving a PWM (pulse width modulation) signal of a microprocessor, and the signal processing control unit reads the current in the output loop of the sampling circuit unit through a microcontroller and changes the duty ratio of the output PWM wave.

Optimally, the starting, stopping and output power of the power supply are controlled by a signal processing control unit, and the signal processing unit of the magnetron power supply completes the following steps in the working of the power supply system:

(1) monitoring output current (I) in real time during power supply operation_out）；

(2) Setting an output current reference value (I)_set）；

(3) Setting a maximum error value (I) of the allowable output current_△）；

(4) Setting the output maximum current value (I)_max）；

(5) Setting output minimum current value (I)_min）；

(6) After starting up, the output current (I) is enabled_out) Slowly increasing;

(7) dynamically adjusting output current value (I)_out) Size;

(8) detecting an open circuit of an output current loop;

(9) detecting short circuit of an output current loop;

(10) and monitoring the temperature of the output power chip.

Further, the magnetron power supply measurement and control scheme is as follows:

(1) when the power supply is started, the PWM duty ratio is gradually increased to a certain proportion and then is kept unchanged, the magnetron filament is preheated, and the PWM duty ratio is continuously increased after 2 seconds until I_outIs close to I_set. The purpose of preheating the magnetron filament is to keep the electron emission capability of the magnetron filament constant in the starting process and avoid damage to the magnetron caused by the instant increase of the filament current;

(2) when in the output loop I_out < I_set-I Δ, increasing the PWM duty cycle. When the current value I in the output loop_out > I_setAt + I Δ, the PWM duty cycle is reduced. When the current value I in the output loop_set+I△< I_out < I_set-the I Δ output PWM duty cycle is maintained constant;

(3) when in the output loop I_out > I_maxWhen the power supply is short-circuited, the power supply enters a protection mode. When in the output loop I_out< I_minWhen the power supply is open, the power supply enters a protection mode;

(4) when the temperature on the power chip exceeds 70 ℃, the output power of the power supply starts to be reduced, and the output power of the power supply gradually decreases along with the temperature rise. When the temperature on the power chip exceeds 85 ℃, the power supply heat dissipation system is considered to be in fault, the power output is closed at the moment, and the power supply enters a protection mode.

The working process of the power supply comprises three stages of starting detection, slow starting and normal operation. After the power supply is powered on, the microprocessor firstly initializes the system, firstly outputs a very small power after the power supply is started, maintains a period of time, and gradually increases the output current after the magnetron outputs stable electronic capacity. And then, slowly starting, firstly, detecting whether the power supply is short-circuited or open-circuited, if the power supply is normal, waiting for the duty ratio to increase to 30%, and after the duty ratio increases to 30%, if the current value of the output loop is smaller than a set value at the moment, indicating that the current magnetron has weak electron emission capability and needs to preheat the filament. And then keeping the duty ratio unchanged at 30%, preheating the lamp filament, and continuously increasing the duty ratio to regulate the current of the output loop after the waiting time is up until the current value in the output loop reaches a set value. If the duty ratio is increased to 30%, the current value in the output loop is larger than a set value, which indicates that the magnetron has normal electron emission capability at the moment, filament preheating is not needed, the duty ratio is continuously increased until the current value in the output loop reaches a preset value, and at the moment, the power supply enters a normal operation stage, and whether the current value in the output loop exceeds the maximum value or is smaller than the minimum value can be monitored in real time at the stage. And if the current value in the output loop is normal, adjusting the PWM duty ratio to enable the current value in the output loop to be stabilized within the set value range. And then reading the temperature value of a temperature probe on a power supply radiator, if the temperature on the radiator exceeds 70 ℃, reducing the output current value, wherein the output current value is reduced by 1/6 of the normal working current value when the temperature rises by 3 ℃, and if the temperature on the radiator exceeds 85 ℃, the output power is reduced to 0, and meanwhile, the output of the drive IC is turned off.

The magnetron power supply measurement and control method provided by the patent can enable the output current of the magnetron power supply in the starting process to be slowly increased, prolong the service life of the magnetron, monitor the output current of the power supply in real time, and can turn off power output if the output current of the power supply is abnormal, thereby avoiding the damage of the power supply.

Drawings

FIG. 1 is a schematic block diagram of a magnetron power supply measurement and control method provided by the invention;

FIG. 2 is a schematic diagram of a power control unit and a sampling unit of a magnetron power measurement and control method provided by the invention;

FIG. 3 is a power supply overall operation flow chart of a magnetron power supply measurement and control method provided by the invention;

FIG. 4 is a power supply startup detection flow chart of a magnetron power supply measurement and control method provided by the invention;

FIG. 5 is a diagram showing the relationship between the PWM duty ratio and the output current in the power supply starting process of the magnetron power supply measurement and control method provided by the invention;

FIG. 6 is a flow chart of the slow power start of the magnetron power measurement and control method according to the present invention;

fig. 7 is a power supply normal operation flow chart of a magnetron power supply measurement and control method provided by the invention.

Detailed Description

The following description of the embodiments of the present invention is provided for illustrative purposes, and other advantages and effects of the present invention will become apparent to those skilled in the art from the present disclosure.

The exemplary embodiments of the present invention will now be described with reference to the accompanying drawings, however, the present invention may be embodied in many different forms and is not limited to the embodiments described herein, which are provided for complete and complete disclosure of the present invention and to fully convey the scope of the present invention to those skilled in the art. The terminology used in the exemplary embodiments illustrated in the accompanying drawings is not intended to be limiting of the invention. In the drawings, the same units/elements are denoted by the same reference numerals.

Unless otherwise defined, terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Further, it will be understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense.

As shown in fig. 1, the magnetron power supply mainly comprises a rectification filter unit, a driving control unit, a sampling circuit unit, a power regulation unit and a signal processing control unit, wherein the rectification filter unit rectifies and filters alternating-current input voltage and then supplies power to a main power loop, and the power switch tube is controlled to be switched on and off by a driving IC IR 2153; the single chip microcomputer sampling circuit unit acquires the current in the power output loop; the power adjusting unit adjusts output power by receiving a PWM signal of the microprocessor; the signal processing control unit reads the output loop current of the sampling circuit unit through the microcontroller STM8S003E3P6, and the duty ratio of the output PWM wave is dynamically adjusted according to the magnitude of the output loop current.

The drive control unit adopts a half-bridge drive chip IR2153 produced by an IR semiconductor company as a PFM modulation chip, the chip is provided with an RC oscillator to generate PFM pulse, the current is amplified and then is sent to a drive output PIN, PIN5 and PIN7 are respectively the output of the controller, PIN5 drives a lower tube LO, PIN7 drives a half-bridge upper tube H, two paths of signals are output in a staggered mode, the switching frequency is controlled between 20 KHZ and 36KHZ, the voltage is regulated through an external singlechip to control the grid voltage of a depletion type MOSFET, the on-resistance of a drain electrode and a source electrode is changed, the R value in an RC oscillation circuit is changed, the charging and discharging speed of a capacitor is changed, and the change of the switching frequency is achieved.

Because the power supply works in a resonance mode, the LC resonance working point of the power supply can be adjusted by changing the frequency, the closer the LC resonance working point is, the smaller the loop impedance is, the more the energy in the resonant cavity is transferred to the output, and conversely, the higher the working frequency is, the larger the loop resonance impedance is, and the smaller the power supply output current is.

As shown in fig. 2, the start, stop and output power of the power supply are controlled by the signal processing control unit. The signal processing control unit is mainly realized by a microprocessor, the sampling circuit converts a current signal in the output loop into a voltage signal and transmits the voltage signal to an AD input port of the microprocessor, and the microprocessor adjusts the duty ratio of an output PWM signal in real time according to the input voltage value of the AD port, so that the output current value of the power supply is stabilized within a fixed range. If the sampling voltage value of the AD port is abnormal, the microprocessor enters a protection mode and turns off the output of the driving signal so as to ensure the self safety of the power supply. The signal processing control unit has the main functions of enabling output current to be increased stably when a power supply is started, enabling current values in an output loop to be stable, monitoring the temperature of a power chip, and self-protecting when the power supply works abnormally, and is a core unit for stable and reliable operation of the power supply.

The overall operation flow of the power supply is as follows: as shown in fig. 3, the power supply operation process includes three stages of power-on detection, slow start and normal operation. The startup detection is used for generating 0-2 s random time delay after startup, so that the power supply damage caused by overlarge impact on a power grid when a plurality of power supplies are started simultaneously is avoided. And detecting whether the power supply output is short-circuited in real time in the process of random time delay. If the output load is short-circuited, the power supply directly enters a protection mode and stops starting. The slow start is used for controlling the power supply to select different starting modes according to the current temperature of the magnetron in the starting process, so that the power supply can be stably started under different conditions, and the damage to the power supply caused by the instant increase of the output current when the magnetron is directly started under the condition of low temperature is avoided. The normal operating stage is used for controlling the power supply to output current and keep stable in the course of the work to real time monitoring power device temperature, if power device IGBT or arrangement bridge BD1 temperature is too high, the power supply will automatically regulated output power, in order to guarantee that power device temperature is in the settlement within range, avoid power device to cause the damage because of the high temperature.

Starting up detection: as shown in fig. 4, after the power supply is powered on, the microprocessor first performs system initialization, and generates a 0-2 s random delay value after the initialization of each part of the function is finished. The main purpose of the random delay is that when a plurality of power supplies are started simultaneously, all the power supplies are started at the same moment, and at this time, the current on the power grid at the input side of the power supply 220 is increased instantly, so that the power grid fluctuation is too large, and the power supplies are easily damaged. And 0-2 s random delay (the delay time interval is 0.1 s) is added, so that when a plurality of power supplies are started simultaneously, the starting time of each power supply is different, and the current on the 220V input side power grid cannot be increased at the same moment. Therefore, the problem that the power grid fluctuation is overlarge when a plurality of power supplies are started at the same time can be effectively avoided. After the random delay value is generated, firstly, the current value in the output loop is read, and then whether the current value exceeds the maximum value in normal operation or not is judged. Because the high voltage is already established after the power supply is powered on, if the load is in a short circuit state at the moment, a large current value exists in the output loop. If the power supply is continuously started without detecting the current value of the output loop, the power supply is damaged. If the current value in the output loop is normal at the moment, the output loop waits until the random delay time is over.

And (3) slow start: when the temperature of the magnetron filament is different, the capability of emitting electrons is different when the magnetron filament is started. In order to enable the output current of the magnetron to be stably increased during starting, a filament preheating process is added during starting. After the power supply is started, a small power is firstly output, a period of time is maintained, and the output current is gradually increased after the magnetron outputs stable electronic capacity.

In fig. 5, the gray curve is a PWM value variation curve, and the black curve is a current value variation curve in the output loop. It can be seen from fig. 5 that after the power supply is started, the magnetron filament has weak electron emission capability, the duty ratio of the PWM wave is not increased after increasing to 300, and then the duty ratio is maintained for 300 for a period of time to preheat the filament, and as the preheating time increases, the filament output electron capability gradually increases, and after the filament electron emission capability is stable, the duty ratio continues to be increased until the current value in the power supply output circuit reaches the set value. After the preheating stage of the lamp filament is added, the output current can be ensured to be stably increased in the starting process of the power supply, and the service life of the magnetron is effectively prolonged.

As shown in fig. 6, after entering the slow start process, first, whether the power supply is short-circuited or open-circuited is detected, if the power supply is normal, the duty cycle is increased to 30%, and after the duty cycle is increased to 30%, if the current value of the output loop is smaller than a set value at this time, it indicates that the current magnetron has a weak electron emission capability and needs to preheat the filament. And then keeping the duty ratio unchanged at 30%, preheating the lamp filament, and continuously increasing the duty ratio to regulate the current of the output loop after the waiting time is up until the current value in the output loop reaches a set value. If the duty ratio is increased to 30%, the current value in the output loop is larger than a set value, which indicates that the magnetron emits electrons normally at the moment, and the duty ratio is continuously increased until the current value in the output loop reaches a preset value without preheating the lamp filament.

And (4) normal operation: as shown in fig. 7, after entering the normal operation phase, it is first determined whether the current value in the output circuit exceeds the maximum value or is smaller than the minimum value. And if the current value in the output loop is normal, adjusting the PWM duty ratio to enable the current value in the output loop to be stabilized within the set value range. And then reading the temperature value of the temperature probe on the heat radiator of the power supply, if the temperature on the heat radiator exceeds 70 ℃, reducing the output current value, wherein the output current value is reduced by 1/6 of the normal working current value every time the temperature rises by 3 ℃, and if the temperature on the heat radiator exceeds 85 ℃, the output power is reduced to 0, and meanwhile, the output of the drive IC is turned off. If the power supply recovers to work normally, the power supply needs to be cut off and restarted. If the temperature is normal, the power supply continuously repeats the steps, detects the current value in the output loop and the temperature value of the radiating fin, and maintains the current value in the output loop to be stable in the set value range.

The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art should be considered to be within the technical scope of the present invention, and the technical solutions and the inventive concepts thereof according to the present invention should be equivalent or changed within the scope of the present invention.