The Huichuan power unit HD90 is the core component of a high-voltage inverter, and its working principle is based on advanced power electronics technology and control strategies. The following is a detailed analysis of its working principle:

1. Power input and phase-shifting transformer processing

Grid access and isolation: The grid voltage is first electrically isolated and voltage level adapted through the main transformer. The transformer adopts a three-phase dry-type rectification design, combined with a forced air cooling system, to ensure long-term stability and safety during operation.

Phase shifted group power supply: The phase shifted transformer decomposes the input high voltage (such as 6kV) into multiple low voltage windings with phase differences (such as the 6kV series containing 18 secondary windings), which use the extended triangle connection method to form specific phase offsets. This design causes the input currents of each power unit to be staggered by a certain angle, effectively suppressing the total harmonic content and meeting the strict requirements of international standards for harmonic distortion.

2. The process of AC-DC-AC conversion

Rectification and filtering stage: Each Huichuan power unit HD90 receives three-phase AC power from a phase-shifting transformer, converts it into DC voltage through a rectifier bridge, and smooths and filters it through capacitors to store energy for subsequent inverter use. The key to this stage is to establish a stable intermediate DC link.

H-bridge inverter and PWM modulation: Using an H-bridge circuit composed of IGBT to perform high-frequency switching control on the DC side electrical energy, generating pulse width modulation (PWM) waveforms. By adjusting the duty cycle to simulate sine wave output, precise voltage and frequency control can be achieved. The application of multiplex PWM technology enables the final output to approach the ideal sine curve, reducing motor harmonic losses and torque ripple.

3. Cascade stacking and star connection synthesis

Unit series topology: Multiple independent power units are connected in series in a star configuration, each responsible for generating a voltage vector at a certain stage. This structure not only improves the system's voltage resistance, but also gradually constructs the required high-voltage three-phase power supply through the principle of stacked wave boosting.

Dynamic balance mechanism: As each unit shares the same control algorithm, they can automatically coordinate the phase relationship, ensuring that the synthesized line voltage maintains symmetry and stability, thereby providing pure variable frequency power supply for high-voltage motors.

4. Huichuan Power Unit HD90 Intelligent Control and Protection System

Vector control algorithm: Based on a high-performance processor platform composed of DSP+ARM+FPGA, it executes complex motor mathematical model calculations and achieves decoupling control of stator current in excitation and torque components. This allows the frequency converter to precisely manage the speed and torque response of AC asynchronous motors, just like controlling DC motors.

Fault redundancy design: When an abnormality occurs in a power unit, the built-in bypass circuit can automatically isolate it and continue to maintain the normal operation of the remaining units. Asymmetric bypass technology further enhances the fault tolerance of the system, allowing it to maintain a high output voltage amplitude even in the event of partial unit failure.

5. Interaction interface and system integration

DCS collaborative work: The frequency converter serves as the executing mechanism to receive analog signal instructions from the distributed control system (DCS), and adjusts the output frequency in real time to match the production process requirements. Simultaneously feedback the operating status parameters to DCS to form a closed-loop control loop.

Human machine interface optimization: The fully Chinese monitoring interface supports local operation and remote network management, making it easy for technical personnel to set parameters, diagnose faults, and trace historical data. The high-speed communication module ensures the efficiency of multi device linkage in large-scale industrial scenarios.