CN110912430B - Method for improving magnetic bias of inverter transformer - Google Patents
Method for improving magnetic bias of inverter transformer Download PDFInfo
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- CN110912430B CN110912430B CN201911160622.XA CN201911160622A CN110912430B CN 110912430 B CN110912430 B CN 110912430B CN 201911160622 A CN201911160622 A CN 201911160622A CN 110912430 B CN110912430 B CN 110912430B
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
- H02M7/42—Conversion of dc power input into ac power output without possibility of reversal
- H02M7/44—Conversion of dc power input into ac power output without possibility of reversal by static converters
- H02M7/48—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M1/00—Details of apparatus for conversion
- H02M1/0003—Details of control, feedback or regulation circuits
- H02M1/0016—Control circuits providing compensation of output voltage deviations using feedforward of disturbance parameters
Abstract
The invention relates to a method for improving the magnetic bias of an inverter transformer, which comprises the following steps: respectively collecting and calculating a positive half-cycle current sampling average value and a negative half-cycle current sampling average value of the primary current; calculating the compensation pulse width according to the positive half cycle current sampling average value and the negative half cycle current sampling average value; compensating the compensation pulse width to positive and negative half-cycle driving pulses; the compensated positive and negative half cycle drive pulses are applied to the main power loop. The invention fully utilizes the on-chip resources of the MCU, acquires the positive and negative half cycle average current in the primary side switching period of the transformer by utilizing a digital technology on the basis of not increasing hardware, and dynamically adjusts and controls the deviation of the forward and reverse pulse width, so that the positive and negative half cycle average values of the primary side current of the main power loop of the transformer of the inverter power supply are equal, the purpose of eliminating magnetic bias is achieved, and the reliability of the inverter power supply is improved.
Description
Technical Field
The invention relates to the field of inverter power supplies, in particular to a method for improving the magnetic bias of an inverter power supply transformer.
Background
The inverter welding power supply has the outstanding advantages of energy conservation, material conservation, good welding performance and the like and is widely applied, but the inverter welding power supply has the outstanding problems of low reliability, easy damage to a power device particularly, and the important reason is that the power device is damaged by overcurrent caused by the magnetic biasing of a power transformer.
Under the influence of factors such as the discreteness of components, the voltage-second product (voltage-second product) of forward and reverse pulse voltages applied to two ends of a main transformer of the inverter power supply is unequal, and the hysteresis working loop of a magnetic core of the transformer deviates from the origin of coordinates; leading to heavy load of power devices and damage of welding power supply in severe cases.
The conventional method for improving the bias of the inverter transformer is to control the peak value of the primary current, and special hardware is needed, so that extra cost is increased.
Disclosure of Invention
The invention aims to provide a method for improving the magnetic bias of an inverter power supply transformer, which enables the average values of positive and negative half cycles of the primary side current of a main power loop of the inverter power supply transformer to be equal on the basis of not increasing hardware, achieves the aim of eliminating the magnetic bias and improves the reliability of the inverter power supply.
The technical purpose of the invention is realized by the following technical scheme:
a method for improving the magnetic bias of an inverter transformer comprises the following steps:
s01: respectively collecting and calculating a positive half-cycle current sampling average value and a negative half-cycle current sampling average value of the primary current;
s02: calculating the compensation pulse width according to the positive half cycle current sampling average value and the negative half cycle current sampling average value;
s03: compensating the compensation pulse width to positive and negative half-cycle driving pulses;
s04: the compensated positive and negative half cycle drive pulses are applied to the main power loop.
By adopting the technical scheme, the on-chip resources of the MCU are fully utilized, on the basis of not increasing hardware, the average current of positive and negative half cycles in the switching period of the primary side of the transformer is obtained by utilizing a digital technology, and the deviation of the forward and reverse pulse widths is dynamically adjusted and controlled, so that the average values of the positive and negative half cycles of the primary side current of the main power loop of the transformer of the inverter power supply are equal, the purpose of eliminating magnetic bias is achieved, and the reliability of the inverter power supply is improved.
The invention is further configured to: the step S01 is preceded by the step S00: the primary current is converted into a waveform through a primary current conversion circuit.
By adopting the technical scheme, the primary side current of the main power loop of the inverter power supply transformer is converted into the waveform which can be collected by the MCU through the primary side current conversion circuit.
The invention is further configured to: the step S00 specifically includes: after the primary current is converted into a waveform through the primary current conversion circuit, the positive half-cycle current and the negative half-cycle current are positive values.
By adopting the technical scheme, the negative half cycle current of the primary side current of the main power loop of the inverter power supply transformer is taken as an absolute value, and a current waveform with positive and negative half cycle currents both being positive values is obtained.
The invention is further configured to: the step S01 specifically includes: the ADC unit samples and converts the positive and negative half-cycle currents of the primary current in a switching period for multiple times, and calculates a sampling average value of the positive half-cycle current and a sampling average value of the negative half-cycle current according to the result of the multiple times of conversion.
By adopting the technical scheme, the on-chip resources of the MCU are fully utilized, and the positive half cycle current sampling average value and the negative half cycle current sampling average value are calculated on the basis of not increasing hardware.
The invention is further configured to: the step S02 specifically includes: and calculating a positive and negative half cycle sampling difference value according to the positive half cycle current sampling average value and the negative half cycle current sampling average value, and multiplying the positive and negative half cycle sampling difference value by a difference ratio coefficient to calculate the compensation pulse width.
By adopting the technical scheme, the on-chip resources of the MCU are fully utilized, and the compensation pulse width is calculated on the basis of not increasing hardware.
The invention is further configured to: the step S03 specifically includes: and compensating the compensation pulse width to positive and negative half-cycle driving pulses, wherein the half cycle with a large average value reduces the pulse width, and the half cycle with a small average value increases the pulse width.
By adopting the technical scheme, the deviation of the forward and reverse pulse widths is dynamically adjusted and controlled, so that the average values of the positive and negative half cycles of the primary current of the main power loop of the transformer of the inverter power supply in the current period are equal, the purpose of eliminating magnetic bias is achieved, and the reliability of the inverter power supply is improved.
In conclusion, the invention has the following beneficial effects: the invention fully utilizes the on-chip resources of the MCU, acquires the positive and negative half cycle average current in the primary side switching period of the transformer by utilizing a digital technology on the basis of not increasing hardware, and dynamically adjusts and controls the deviation of the forward and reverse pulse width, so that the positive and negative half cycle average values of the primary side current of the main power loop of the transformer of the inverter power supply are equal, the purpose of eliminating magnetic bias is achieved, and the reliability of the inverter power supply is improved.
Drawings
FIG. 1 is a schematic diagram of the process of example 1;
FIG. 2 is a waveform diagram of a primary current;
FIG. 3 is a schematic diagram of a converted waveform of a primary current;
FIG. 4 is a schematic diagram of the MCU sampling positive and negative half cycles of the primary current respectively;
fig. 5 is a schematic diagram of positive and negative half cycle drive pulses before and after compensation.
Detailed Description
The present invention will be described in further detail with reference to the accompanying drawings.
The noun explains:
MCU, Microcontroller Unit, microcontrol Unit;
ADC, Analog-to-Digital Converter.
Example 1: a method for improving the magnetic bias of an inverter transformer, as shown in fig. 1, includes the following steps:
s01: respectively acquiring and calculating a positive half-cycle current sampling average value and a negative half-cycle current sampling average value of a primary current (of a main power loop of an inverter power supply transformer);
s02: calculating the compensation pulse width according to the positive half cycle current sampling average value and the negative half cycle current sampling average value;
s03: compensating the compensation pulse width to positive and negative half-cycle driving pulses (for controlling the work of an inverter power transformer);
s04: the compensated positive and negative half cycle drive pulses are applied to the main power loop (inverter transformer).
Example 2: the difference from embodiment 1 is that the step S01 is preceded by a step S00: the primary side current of the main power loop of the inverter power supply transformer is converted into a waveform which can be collected by the MCU through the primary side current conversion circuit.
Example 3: the difference from embodiment 2 is that step S00 specifically includes: after the primary current of the main power loop of the inverter power supply transformer is converted by the primary current conversion circuit, the positive half-cycle current and the negative half-cycle current are positive values.
As shown in fig. 2 and 3, fig. 2 is a waveform diagram of the primary side current, and fig. 3 is a waveform diagram of the primary side current after conversion, that is, the absolute value of the negative half cycle current of the primary side current is taken.
Example 4: the difference from embodiment 1 is that step S01 specifically includes: and a high-speed ADC unit in the MCU is used for sampling and converting the positive and negative half-cycle currents of the primary side current of the main power loop of the inverter power supply transformer in a switching period for multiple times, and calculating a sampling average value of the positive half-cycle current and a sampling average value of the negative half-cycle current according to the result of the multiple times of conversion.
As shown in fig. 4, fig. 4 is a schematic diagram that the MCU samples the positive and negative half cycles of the primary current respectively, the MCU collects the positive and negative half cycles of the primary current for multiple times, and the sampling points of the positive and negative half cycles are as shown in fig. 4; the positive half cycle current sample average of S1.. Sn and the negative half cycle current sample average of S (n +1) … S2n were calculated, respectively.
Example 5: the difference from embodiment 1 is that step S02 specifically includes: and calculating a positive and negative half cycle sampling difference value according to the positive half cycle current sampling average value and the negative half cycle current sampling average value, and multiplying the positive and negative half cycle sampling difference value by a difference ratio coefficient to calculate the compensation pulse width. The difference ratio coefficient is a constant, and different systems may set a coefficient.
Example 6: the difference from embodiment 1 is that step S03 specifically includes: compensating the compensation pulse width to positive and negative half-cycle driving pulses for controlling the work of the inverter transformer, wherein the half cycle with the larger average value reduces the corresponding compensation pulse width, and the half cycle with the smaller average value increases the corresponding compensation pulse width.
As shown in fig. 5, fig. 5 is a schematic diagram of positive and negative half-cycle driving pulses before and after compensation, and the average value of the positive half-cycle driving pulses (dotted lines) before compensation is large, so as to reduce the corresponding compensation pulse width; the average value of the negative half-cycle driving pulse (dotted line) before compensation is small, and the corresponding compensation pulse width is increased.
The present embodiment is only for explaining the present invention, and it is not limited to the present invention, and those skilled in the art can make modifications of the present embodiment without inventive contribution as needed after reading the present specification, but all of them are protected by patent law within the scope of the present invention.
Claims (3)
1. A method for improving the magnetic bias of an inverter transformer is characterized by comprising the following steps:
s01: respectively collecting and calculating a positive half-cycle current sampling average value and a negative half-cycle current sampling average value of the primary current;
s02: calculating the compensation pulse width according to the positive half cycle current sampling average value and the negative half cycle current sampling average value;
s03: compensating the compensation pulse width to positive and negative half-cycle driving pulses;
s04: applying the compensated positive and negative half-cycle driving pulses to a main power loop;
wherein, the step S01 specifically includes: the ADC unit samples and converts the positive and negative half-cycle currents of the primary current in a switching period for multiple times, and calculates a sampling average value of the positive half-cycle current and a sampling average value of the negative half-cycle current according to the result of the multiple times of conversion;
the step S02 specifically includes: calculating a positive and negative half cycle sampling difference value according to the positive half cycle current sampling average value and the negative half cycle current sampling average value, and multiplying the positive and negative half cycle sampling difference value by a difference ratio coefficient to calculate a compensation pulse width, wherein the difference ratio coefficient is a constant;
the step S03 specifically includes: and compensating the compensation pulse width to positive and negative half-cycle driving pulses, wherein the half cycle with a large average value reduces the pulse width, and the half cycle with a small average value increases the pulse width.
2. The method for improving the magnetic bias of the transformer of the inverter power supply as claimed in claim 1, wherein the step S01 is preceded by the step S00: the primary current is converted into a waveform through a primary current conversion circuit.
3. The method for improving the bias of the transformer of the inverter power supply as claimed in claim 2, wherein the step S00 is specifically as follows: after the primary current is converted into a waveform through the primary current conversion circuit, the positive half-cycle current and the negative half-cycle current are positive values.
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| CN113839551A (en) * | 2020-06-23 | 2021-12-24 | 中兴通讯股份有限公司 | Pulse width compensation method, pulse width compensation device, storage medium and electronic device |
| CN112701937B (en) * | 2020-12-16 | 2023-09-26 | 河南海格经纬信息技术有限公司 | Method for inhibiting DC magnetic bias of DC converter transformer |
| CN112564536B (en) * | 2021-02-20 | 2021-05-14 | 深圳英飞源技术有限公司 | Wave-by-wave current limiting control method and device of inverter circuit |
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| TW200610254A (en) * | 2004-09-07 | 2006-03-16 | Sysgration Ltd | Demagnetization circuit applied in push-pull circuit |
| CN101741252A (en) * | 2010-02-11 | 2010-06-16 | 湘潭电机股份有限公司 | Direct-current power supply voltage stabilizer of accessory system for large-scale mine electric locomotive |
| CN102435810A (en) * | 2011-09-14 | 2012-05-02 | 北京国基科技股份有限公司 | Method and device for detecting direct-current component in alternating current |
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