Reducing the losses of solar inverters requires starting from multiple aspects such as circuit design, control strategy, hardware optimization, etc. The following are specific methods and technical details:
1、 Optimization of Circuit Topology and Device Selection
Adopting soft switching technology
Optimize MPPT efficiency in DC-DC stage (such as using interleaved Boost topology to reduce inductance ripple);
During the DC-AC stage, SVPWM modulation is used to improve voltage utilization to over 90% (15% higher than traditional SPWM).
Zero Voltage Switching (ZVS)/Zero Current Switching (ZCS): By using a resonant circuit, power devices can achieve zero voltage or current at the moment of switching, eliminating switching losses (such as in phase-shifting full bridge ZVS topology, where switching losses are reduced by more than 40%).
Multi level transformation structure: divided into "DC-DC boost+DC-AC inverter" two-stage control, for example:
Application of Low Loss Power Devices
Fill the gap between the device and the heat sink with silicone with a thermal conductivity greater than 5W/m · K to reduce thermal resistance;
During forced air cooling, the wind speed should be controlled at 3-5m/s to maintain the IGBT junction temperature below 80 ℃ (with a 5% increase in conduction loss for every 10 ℃ increase).
The switching speed of SiC MOSFET reaches over 100kHz (IGBT usually<20kHz), and the switching loss is reduced by 50%;
The on resistance of GaN HEMT is only 1/10 of that of Si devices of the same specification, making it suitable for high-frequency scenarios (such as inverters above 100kW).
2、 Control Algorithm and MPPT Optimization
Dynamic MPPT algorithm upgrade
For every 1 ℃ increase in temperature, the open circuit voltage of the photovoltaic panel decreases by 0.3%, and the algorithm automatically compensates for the MPPT voltage reference.
Adaptive variable step perturbation observation method: Adjust the step size in real-time based on changes in lighting conditions (such as 0.1% step size for stable lighting and 5% step size for sudden changes), reducing tracking error from 3% to within 1%.
Fuzzy logic+neural network composite control: Establish a temperature voltage power mapping model, for example:
PWM modulation and harmonic suppression
SVPWM+multilevel technology: Three level topology (such as NPC topology) reduces the output voltage harmonic THD from 5% to below 2%, reducing line harmonic losses.
Carrier phase shifting technology: When multiple modules are connected in parallel, the carrier phase of each module is shifted, effectively increasing the switching frequency and reducing the output current ripple (such as shifting two modules by 180 ° and halving the ripple amplitude).
3、 Magnetic components and circuit optimization
Application of high-frequency and low loss magnetic materials
The planar transformer adopts multi-layer PCB windings to reduce skin effect at high frequencies (at 100kHz, the copper loss of circular wires is twice that of planar windings);
The inductor adopts segmented winding and interleaving technology, reducing leakage inductance by 30%.
High frequency range (20-100kHz) uses ferrite PC95 material (loss<200mW/cm ³ at 100kHz), which has a 60% lower loss than silicon steel sheets;
Capacitor and Line Loss Reduction
The cross-sectional area of the copper bar is selected based on a current density of<4A/mm ² (e.g. 25mm ² copper bar is used for 100A current), and the line resistance is<1m Ω;
Using stacked busbars to reduce stray inductance (for every 10nH decrease in stray inductance, the switch peak voltage drops by 10V).
Replacing electrolytic capacitors (ESR>50m Ω) with thin-film capacitors (ESR<10m Ω) for DC busbars reduces ripple losses by 70%;
Multi layer ceramic capacitors (MLCC) are used for output filtering, with lower impedance at high frequencies.
4、 Load matching and thermal management
Wide load efficiency optimization strategy
When the load is less than 30%, enable the "sleep mode" and turn off half of the power devices (such as a three-phase inverter running only two phases), increasing the light load efficiency from 85% to 92%;
When the load exceeds 80%, activate the "full power mode" and increase the switching frequency to the rated value to avoid current limiting losses.
Multi mode switching control:
LLC resonant topology application: maintains an efficiency of over 96% in the load range of 40% -100% (traditional hard switch topology efficiency drops to 90% under light load).
Intelligent thermal management and loss balancing
Gate series matching resistor (error<1%), making the current imbalance of parallel IGBT less than 5%;
Add an active current sharing circuit to adjust the delay of the driving signal in real time, further reducing losses.
Liquid cooled cooling system: The cooling liquid is deionized water+ethylene glycol (volume ratio 7:3), and when the flow rate is 2L/min, the device junction temperature fluctuation is<5 ℃ (air cooling fluctuation>15 ℃).
5、 System Integration and Maintenance Strategy
Modular and redundant design
Parallel redundancy of power modules: For example, a 10kW inverter consists of 5 2kW modules, and in the event of a single module failure, the remaining modules can operate at full capacity, increasing system availability from 98% to 99.9%.
Hot swappable design: supports live replacement of faulty modules, reducing downtime losses (traditional inverters lose about 0.5% of power generation per maintenance shutdown).
Real time monitoring and preventive maintenance
Through the above measures, the efficiency of the inverter can be increased from 96% to over 98.5%, and an additional power generation of about 150000 kWh can be achieved within a 10-year cycle, which is equivalent to reducing 150 tons of CO ₂ emissions and significantly improving the economic and environmental benefits of the photovoltaic system.
