Temperature control of solar inverter: active regulation strategy (core classification+common engineering scheme)
Active temperature control is to actively intervene in heat dissipation/heating through controllable actuators and closed-loop logic, which is different from passive methods such as natural heat dissipation and passive heat conduction. It is suitable for high-power, wide-temperature range and high-reliability photovoltaic inverters (commonly used for series, centralized and energy-storage parallel-grid inverters).
First, basic active heat dissipation (the most mainstream)
PWM speed regulating fan control
According to the temperature of power module/IGBT/SiC MOSFET, ambient temperature and output power, step by step/continuous speed regulation.
Strategy: low temperature and low rotation noise reduction, medium temperature routine, high temperature full rotation; Support start-stop return error and prevent frequent jitter
Active air cooling (multi-fan zoning/redundant control)
Multi-fan independent control: full start at high temperature, partial start at medium temperature and low stop at low temperature.
Redundancy strategy: If a single fan fails, the rotating speed of other fans will be automatically increased, with no derating or less derating.
Active circulation control of liquid cooling
Water cooling plate+electronic water pump PWM speed regulation, adjust the flow according to the temperature of power device and the temperature difference between the inlet and outlet of coolant.
Centralized/high-power industrial and commercial inverters are commonly used, with more stable temperature control and lower noise.
Second, active power limiting/dynamic derating (temperature control core protection strategy)
Temperature-power closed-loop power limiting
Set multi-level thresholds: early warning → light power limit → deep power limit → shutdown protection.
Control objects: IGBT/SiC junction temperature, radiator temperature, capacitor temperature and indoor environment temperature.
Active power limiting based on junction temperature estimation
Combined with current, switching frequency and loss model, the junction temperature is estimated in real time, and the power is limited in advance to avoid passive triggering after over-temperature.
Ambient temperature compensation limited power
Lower the upper power limit in advance in high temperature environment/high altitude (poor heat dissipation) to prevent heat accumulation.
III. Active heating (required for low-temperature startup/extremely cold areas)
Active constant temperature control of PTC/heating film
Preheating before starting at low temperature (such as below-20℃): capacitors, drivers, DSP, power devices and bus capacitors.
Strategy: The working temperature zone is automatically closed to prevent overheating and energy waste.
Self-heating (heating by power device loss)
Light/no-load injection of small current produces loss heating, which is suitable for machines without special heating hardware.
IV. Active temperature control at circuit/topology level (reducing heat from the source)
Active adjustment of switching frequency
High temperature/heavy load: reduce switching frequency, reduce switching loss and temperature rise.
Low temperature/light load: restore high frequency to improve efficiency/harmonic performance.
Multi-bridge arm/multi-channel current sharing/rotation work
Multi-phase/multi-module parallel connection: automatically share current to avoid overheating of single module.
The load of the high-temperature module is appropriately reduced, and the low-temperature module is replenished, so that the overall temperature is balanced.
Self-adaptation of dead time and driving intensity
Optimize driving parameters at high temperature, reduce on/off loss, and indirectly control temperature.
Five, intelligent and collaborative active strategy
MPPT coordinated temperature control
Moderately relax the MPPT voltage point, reduce the DC side current and reduce the loss of the whole machine when the temperature is over.
Differential temperature control in grid/off-grid mode
Off-grid belt inductive/impact load: improve heat dissipation capacity in advance
Grid-connected high-power long-term operation: more radical heat dissipation/power limiting logic
Predictive temperature control (predictive regulation)
Based on irradiation, power trend and change rate of ambient temperature, start the fan/pre-limit power in advance to avoid sudden temperature shock.
Fault degradation temperature control
Fan/sensor failure: quickly enter the strict power limit+periodic inspection to maintain the operational state.
Six, typical temperature control logic (simplified closed-loop process)
Acquisition: IGBT/radiator/environment/capacitor temperature, output power and DC voltage.
Judgment: Graded temperature range (normal temperature/early warning/high temperature/overtemperature/low temperature)
Execute:
Low temperature → active heating
Normal temperature → low fan speed/stop, full power operation.
Medium temperature → medium speed fan, no derating.
High temperature → full fan speed+step power limit
Over-temperature → emergency power limit to 0/shutdown protection
Summary: Common combinations in engineering (high cost performance)
Household/small series inverter: PWM fan+temperature grading power limit+low temperature self-heating.
Industry and commerce/high power: liquid cooling/strong fan air cooling+multi-module current sharing+switching frequency adaptation+junction temperature estimation power limit.
