The application areas and methods for shunt resistors in inverters/photovoltaic/wind/hydro/hydrogen and instrumentation equipment
author: Milliohm Electronics
2025-05-26
Instrumentation equipment
- High-precision measurement
Application: 10A range of digital multimeter (such as Fluke 87V)
Method: Use a four-wire manganese copper shunt (0.01Ω±0.1%) to eliminate lead error
Method: Use a four-wire manganese copper shunt (0.01Ω±0.1%) to eliminate lead error
- Industrial process control
Application: PLC analog input module (such as Siemens SM331).
Method: Convert 4-20mA signal to voltage and collect it through 24-bit ADC
Method: Convert 4-20mA signal to voltage and collect it through 24-bit ADC
- Battery testing equipment
Application: Charge and discharge tester (such as Chroma 17011).
Method: Multi-range shunt automatically switches, covering the range of μA to 100A
Method: Multi-range shunt automatically switches, covering the range of μA to 100A
Inverter system
- DC bus current detection
Location: Connected to the DC input side, close to the capacitor or IGBT module.
Method: By measuring the voltage across the shunt, the input current is monitored in real time for overload protection and efficiency optimization.
Method: By measuring the voltage across the shunt, the input current is monitored in real time for overload protection and efficiency optimization.
- AC output current feedback
Location: Inverter output (L/N line)
Method: Cooperate with the PWM controller to adjust the switching frequency to ensure stable sine wave output.
Method: Cooperate with the PWM controller to adjust the switching frequency to ensure stable sine wave output.
- IGBT/MOSFET current protection
Location: Power device source/emitter.
Method: Detect instantaneous current, trigger short-circuit protection, and prevent device damage.
Method: Detect instantaneous current, trigger short-circuit protection, and prevent device damage.
Photovoltaic system
- MPPT controller
Location: between the output end of the photovoltaic array and the DC-DC converter
Method: combine the voltage sensor to calculate the power and dynamically adjust the working point to the maximum power output
Method: combine the voltage sensor to calculate the power and dynamically adjust the working point to the maximum power output
- Combiner box monitoring
Location: the negative circuit of each string of photovoltaic modules
Method: multi-channel shunts monitor the current of each branch and quickly locate the faulty string (such as shadowing)
Method: multi-channel shunts monitor the current of each branch and quickly locate the faulty string (such as shadowing)
- Grid-connected inverter
Location: output end of the inverter AC side
Method: ensure that the grid-connected current harmonics meet the standards (such as THD <5%)
Method: ensure that the grid-connected current harmonics meet the standards (such as THD <5%)
Wind energy system
- Generator side current detection
Location: Doubly fed asynchronous generator rotor circuit
Method: Control rotor current frequency to achieve variable speed constant frequency operation
Method: Control rotor current frequency to achieve variable speed constant frequency operation
- Converter DC link
Location: DC bus between rectifier and inverter
Method: Balance the energy flow between generator and grid to prevent bus voltage fluctuation
Method: Balance the energy flow between generator and grid to prevent bus voltage fluctuation
- Power supply monitoring of variable pitch system
Location: Variable pitch motor drive circuit
Method: Monitor motor current to ensure accurate blade angle adjustment
Method: Monitor motor current to ensure accurate blade angle adjustment
Hydrogen energy system
- Electrolyzer current control
Location: DC power input terminal of alkaline or PEM electrolyzer
Method: Accurately control kiloampere current (such as 1kA@2V) to improve hydrogen production efficiency
Method: Accurately control kiloampere current (such as 1kA@2V) to improve hydrogen production efficiency
- Fuel cell stack monitoring
Location: cathode/anode gas path of single cell in the stack
Method: Detect single cell current density to avoid local overload
Method: Detect single cell current density to avoid local overload
- Hydrogen station compressor drive
Location: DC side of motor drive inverter
Method: Real-time current limiting protection to prevent compressor overload
Method: Real-time current limiting protection to prevent compressor overload
Hydropower system
- Hydrogenerator output
Location: neutral point of generator stator winding.
Method: detect three-phase unbalanced current and protect winding insulation
Method: detect three-phase unbalanced current and protect winding insulation
- Speed governor excitation control
Location: exciter output circuit
Method: adjust excitation current to stabilize output voltage
Method: adjust excitation current to stabilize output voltage
- Grid-connected synchronization detection
Location: front side of circuit breaker grid-connected
Method: match grid phase to prevent impact current
Method: match grid phase to prevent impact current
Key design considerations
- Heat dissipation design: Water-cooled shunts are used for megawatt-level inverters to reduce temperature drift to below 50ppm/℃
- Signal processing: Instrumentation amplifiers (such as AD8421) are used to suppress common-mode noise and improve signal-to-noise ratio
- Resistance optimization: Milliohm-level shunts (such as 0.1mΩ/500A) are used for electrolyzers, and ohm-level shunts are used for instruments
- Material selection: Shunts for wind/photovoltaic power need to withstand temperature differences (-40℃~85℃), and hydrogen energy systems require explosion-proof packaging
Through the above applications, shunt resistors play a key role in improving system efficiency, ensuring safe operation, and achieving high-precision measurements. The actual selection needs to be weighed based on the current range, environmental conditions, and accuracy requirements.
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