1. Rectification part: energy-saving IGBT medium frequency power supply rectification adopts three-phase semi-controllable mode, and thyristor is only used as a switch, that is, the voltage after rectification is always maintained at 500V whenever the device is started, and does not change with the power, so The generation of harmonics is greatly reduced, and harmonic interference to the power grid is alleviated. The rectification control part adopts PLD control, which is connected with the IGBT intermediate frequency main board through four wires, two of which are used as the starting rectification line, and the other two are used as the stop and protection signal lines.
2. Filtering part: IGBT intermediate frequency adopts two kinds of methods: reactor filter and electrolytic capacitor filter. The reactor filter can make the current continuous, and the electrolytic capacitor filter can make the voltage constant, so that the inverter can obtain a stable voltage source and current source. .
3. Inverter part of IGBT module: The inverter part adopts IGBT half-bridge series inverter, and the inverter component is FZ400R12KE3 IGBT module produced by Siemens of Germany. This module is a module with positive temperature coefficient, that is, when the temperature rises Its on-state impedance will increase, which facilitates current sharing between multiple IGBT modules.
4. IGBT module drive: The drive part adopts SKHI 26W drive board produced by Germany Ximenkang Co., Ltd. This drive board has strong drive capability, perfect protection function, and can drive 6 IGBT modules, with overcurrent and overvoltage protection functions. The graded drive board is a good guarantee for reliable operation of the equipment.
5. Drive power supply: The drive power supply adopts the isolated power supply module, that is, the “ground” of the drive power supply is isolated from the external power supply, so as to avoid the influence of external interference, which is beneficial to the reliable operation of the device.
6, the main control board has the following functions
A. Pulse synthesis function: The main control board divides the single pulse signal into two pulses through the JK flip-flop, and then combines this signal into two symmetric two-way pulses through a series of logic gate circuits. The dead time is adjustable.
B. Frequency tracking function: The main control board synthesizes the channel signal and the voltage of the power potentiometer into a composite voltage signal, and controls the output frequency of the voltage controlled oscillator through the voltage signal, so that the output frequency on the circuit board always follows the slot. Road frequency. Note: The potentiometer is essentially adjusting the commutation angle.
C. Synchronous protection function: When the slot frequency is not synchronized with the trigger output pulse frequency on the main control board, the device power will be automatically reduced to the minimum, which is beneficial to protect the device.
D. Overcurrent and current limiting functions: The IGBT IF main control board has two overcurrent and current limiting functions, one from the three-phase incoming line and the other from the induction coil. When the set current value is exceeded, the main control board will report an overcurrent fault and automatically stop the equipment operation; when the output current reaches the specified current, the main control board will perform current limiting and stabilize the current at the set The current value is unchanged, and the constant power operation is reached at this time.
E. Water temperature and water pressure protection function: The IGBT intermediate frequency main control board monitors the temperature of the circulating water through the temperature sensor. When the water temperature exceeds the specified temperature, the main control board will alarm and automatically stop the equipment operation; the IGBT intermediate frequency main control board has both Water pressure protection function, because the IGBT intermediate frequency adopts internal and external two cycles, the water pressure protection is divided into internal water pressure and external water pressure alarm. When the water pressure is lower than the set water pressure value, the main control board will alarm and automatically stop the equipment. run.
