Digital reliability
Hard switching technology
The so-called hard-switching PWM refers to the switching power supply that is commonly referred to in the power conversion process, which refers to a hard switching power supply. In this kind of power supply, the switching device (switching tube) is turned on or off under the condition of withstanding voltage and current, so a large loss, that is, a switching loss, is generated during the turning on and off. When the working state of the power supply is constant, the loss of the switching device being turned on or off once is also certain, so the higher the switching frequency, the greater the switching loss. At the same time, during the switching process, the oscillation of the distributed inductance and parasitic capacitance of the circuit will be stirred, which will bring additional loss and generate electromagnetic interference. Therefore, the frequency of the hard switching power supply cannot be too high, and measures to prevent electromagnetic interference must be taken. The reliability and efficiency are poor. Low, electromagnetic interference is extremely serious, therefore, hard-switching PWM technology can not meet the requirements of technological progress. At present, quite a lot of high-power switching power supplies developed in China use hard-switching PWM control.
Soft switching technology
The so-called soft switching power supply is relative to the hard switching power supply, which is a revolutionary development compared to the hard switching PWM technology. It has improved the reliability, efficiency and electromagnetic interference (EMI) of the power supply products to a considerable extent. The switching device of the soft switching power supply is either turned on or off, or the voltage applied to it is zero (ZVS), that is, zero voltage switching, or the current through the switching device is zero (ZCS), that is, zero current switch. This switching method significantly reduces the oscillations caused by the switching loss during switching, and can greatly increase the switching frequency, creating conditions for miniaturization and high efficiency of the switching power supply.
The Sigma welder adjusts the output voltage by changing the magnitude of the phase shift voltage of the lower switch tube on the diagonal of the full bridge, so that the voltage on the control pole of the super-forearm switch is ahead of the voltage on the control pole of the lag arm switch. At the control end of the controller, different dead time is set for the two inverting driving voltages of the same bridge arm, and the resonant process is completed by using the leakage inductance of the transformer and the junction capacitance of the switching tube and the parasitic capacitance between the primary and secondary of the transformer. The zero voltage is turned on and off, staggering the hard switching state of the switching device with large current and high voltage at the same time, suppressing the inductive turn-off voltage spike and the tube temperature when capacitive opening is too high, reducing switching loss and interference.
EMC electromagnetic compatibility
Electromagnetic compatibility (EMC) refers to the ability of a device or system to operate in its electromagnetic environment without causing unacceptable electromagnetic interference to any device in its environment. Therefore, EMC includes two requirements: The electromagnetic interference generated by the equipment in the normal operation process shall not exceed a certain limit; on the other hand, the appliance has a certain degree of immunity to the electromagnetic interference existing in the environment, that is, electromagnetic sensitivity. Ordinary welding machine Without this function, the pollution to the power grid is very serious, which has a great impact on precision instruments. At present, China is preparing to implement EMC mandatory testing.
Key test equipment
Constant temperature room: Our products are tested at an ambient temperature of 40 ° C, so under the same load factor, our products have the ability to work continuously in high strength and harsh environment, with very high reliability and durability. .
LECROY oscilloscope Wave Surfer 44Xs.
The main operating frequency is: 400MHz.
Input channel: 4 channels of electrical signals can be tested simultaneously.
Data Collector: Agilent 34970A
Infrared thermometer: Non-contact temperature tester.
The reliability of digitalization also includes overcurrent protection, overheat protection, temperature protection, overvoltage protection, instantaneous high voltage protection, insulation measures—insulation IGBT module, immersion protection—high-strength varnish material and Process, rich alarm code, etc.
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