What is an IGBT CCR?
A constant current regulator that switches the power with IGBTs at high frequency — filtered into the loop current and corrected by a closed control loop.
An IGBT CCR uses insulated-gate bipolar transistors as fast electronic switches in a switch-mode power stage. The supply is rectified to DC, the IGBT bridge switches it at high frequency with a varying pulse width, and a filter and output transformer turn the pulses into the loop current. A current sensor and controller correct the pulse width every cycle to hold the current at the selected step.
Unlike a thyristor, an IGBT can be switched off at any instant, so control is faster and finer and the output can be cleaner. The design is compact and efficient, but it relies on power modules, gate-drive boards and good cooling, and it needs surge protection. The DC-bus capacitors hold charge, so wait and measure before opening the unit, and never open a live series circuit.
- Rectify. The supply is converted to a DC voltage on the DC bus.
- Switch. The IGBT bridge switches the DC on and off at high frequency, with a varying pulse width.
- Filter. A filter and the output transformer smooth the pulses and isolate the loop.
- Deliver. The series loop receives the set current for the selected step.
- Measure. A current sensor feeds the output current back to the controller.
- Correct. The controller changes the pulse width through the gate drive to hold the set value.
Frequently Asked Questions
Q1What is an IGBT CCR?
A constant current regulator whose power stage uses insulated-gate bipolar transistors (IGBTs) as fast electronic switches. The supply is rectified to DC, the IGBTs switch it at high frequency with a varying pulse width, a filter and output transformer turn the pulses into the loop current, and a controller holds that current at the selected step.
Q2How is it different from a thyristor CCR?
A thyristor CCR chops each half-cycle of the mains at a chosen firing angle, and each thyristor can only turn off at the next zero crossing. An IGBT can be switched on and off at any moment, thousands of times a second, which gives faster and finer control and a cleaner output waveform.
Q3Why is the output current more accurate?
A current sensor on the output feeds the controller many times per cycle, and the controller changes the pulse width at once to correct any error. The high switching frequency also lets a small filter smooth the output towards a clean waveform. Actual accuracy depends on the design and the manufacturer's data.
Q4Does it still need a transformer?
Usually yes. An output transformer isolates the series loop from the supply and sets the voltage the loop needs. Where the loop current is a mains-frequency output, the transformer works at mains frequency, as in other designs. Some designs use a high-frequency isolation stage, which can make the transformer smaller and lighter, so the arrangement varies by maker.
Q5What should be checked on an IGBT CCR?
Cooling and fans, the DC-bus capacitors, connections and terminals, the alarm and event log, and the output current on every step compared with the commissioning baseline. Power modules and gate-drive boards are normally replaced as units, so keep suitable spares.
Q6What are the main safety points?
Never open a live series circuit, since the CCR keeps driving current and the voltage across the break can rise dangerously. Isolate and lock out the supply, prove it dead, and wait for the DC-bus capacitors to discharge, then confirm it by measurement before working inside the unit.
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