Mains 230 V Photovoltaic Inverter = Class D !?!
A friend's home mains tied PV inverter just failed and the solar power companies seem to do no repairs, just sell a new one, so I scored the old inverter.
It's an Aurora PVI 3600-AU, as you would expect from the model code it's 3600 watts, Australian 230 V model.
It may not be repairable, it's all driven by a micro controller and there's no source code, or schematics, or service manual, AFAIK.
But the failure was an "Over Temperature" even with no sun and the inverter stone cold so maybe just a bad temperature sensor
In any case it should have some useful bits inside and it will at least be educational to pull it apart.
The inverter core is basically a 3.6 kW Class D amp that is fixed on 50 Hz so I wondered if anyone here had pulled one apart?
What does the screw labelled "Warranty Void if Removed" do?😉
David
A friend's home mains tied PV inverter just failed and the solar power companies seem to do no repairs, just sell a new one, so I scored the old inverter.
It's an Aurora PVI 3600-AU, as you would expect from the model code it's 3600 watts, Australian 230 V model.
It may not be repairable, it's all driven by a micro controller and there's no source code, or schematics, or service manual, AFAIK.
But the failure was an "Over Temperature" even with no sun and the inverter stone cold so maybe just a bad temperature sensor
In any case it should have some useful bits inside and it will at least be educational to pull it apart.
The inverter core is basically a 3.6 kW Class D amp that is fixed on 50 Hz so I wondered if anyone here had pulled one apart?
What does the screw labelled "Warranty Void if Removed" do?😉
David
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Here's what you could do without removing any screws:
Check for shorts between each output and the bus capacitor terminals. If positive, then the corresponding MOSFET/IGBT could be the primary reason for damage. Similarly, a short circuit across the bus capacitor indicates at least one fully blown leg within the inverter. In both these cases, the inverter could be repaired without a service manual.
However, even if both the control and power stages are OK, there still could be a gate-driver failure. Even though a repair would remain possible in this case, a service manual may be necessary. Now, if the failure is within the control section, then it may not be possible to repair the inverter, even with a service manual, unless attempted by the manufacturers themselves.
Please note that at times a primary damage could be cleared by replacing a MOSFET etc., but the inverter would not become functional until any secondary damages that may have occurred (due to the blown MOSFET) have also been cleared. This kind of cascaded failure is fairly common in power converters.
Well, similar but not quite a class-D amp, as its reference is not fixed and can change frequency/phase (like in a PLL) to allow for synchronisation to the grid voltage. Besides, it may also have an MPP tracker algorithm that ensures maximum possible panel utilisation for a given solar irradiance. Further, most single-phase inverters are modulated using a method known as "unfolding" (idea here) that is usually not preferred by class-D designers (for obvious reasons). Nevertheless, the PWM portion is common to both applications, provided the inverter is single-phase, while three-phase inverters generally tend to use space vector modulation instead.
The de-saturation circuits (within gate-drivers) cut the gate pulses to a device as soon as the conducting voltage-drop across the device crosses a threshold (possibly due to a damage). However, if such a fault elevates the temperature even momentarily (thermal cycle) and the fault is programmed to be "latched", then the over-temperature warning could continue even after the temperature falls, until cleared by a manual reset.
Do keep in mind that the damage could also have happened from the permanently connected grid-side (due to lightning/over-voltage etc.) in which case it would be a good idea to (casually) ask around the neighbourhood if any over-voltages/grid-tie mishaps were reported around the time.
Well, now that the manufacturer has refused to repair the inverter, I think you may start removing screws without any consequences. 🙂
Check for shorts between each output and the bus capacitor terminals. If positive, then the corresponding MOSFET/IGBT could be the primary reason for damage. Similarly, a short circuit across the bus capacitor indicates at least one fully blown leg within the inverter. In both these cases, the inverter could be repaired without a service manual.
However, even if both the control and power stages are OK, there still could be a gate-driver failure. Even though a repair would remain possible in this case, a service manual may be necessary. Now, if the failure is within the control section, then it may not be possible to repair the inverter, even with a service manual, unless attempted by the manufacturers themselves.
Please note that at times a primary damage could be cleared by replacing a MOSFET etc., but the inverter would not become functional until any secondary damages that may have occurred (due to the blown MOSFET) have also been cleared. This kind of cascaded failure is fairly common in power converters.
Well, similar but not quite a class-D amp, as its reference is not fixed and can change frequency/phase (like in a PLL) to allow for synchronisation to the grid voltage. Besides, it may also have an MPP tracker algorithm that ensures maximum possible panel utilisation for a given solar irradiance. Further, most single-phase inverters are modulated using a method known as "unfolding" (idea here) that is usually not preferred by class-D designers (for obvious reasons). Nevertheless, the PWM portion is common to both applications, provided the inverter is single-phase, while three-phase inverters generally tend to use space vector modulation instead.
The de-saturation circuits (within gate-drivers) cut the gate pulses to a device as soon as the conducting voltage-drop across the device crosses a threshold (possibly due to a damage). However, if such a fault elevates the temperature even momentarily (thermal cycle) and the fault is programmed to be "latched", then the over-temperature warning could continue even after the temperature falls, until cleared by a manual reset.
Do keep in mind that the damage could also have happened from the permanently connected grid-side (due to lightning/over-voltage etc.) in which case it would be a good idea to (casually) ask around the neighbourhood if any over-voltages/grid-tie mishaps were reported around the time.
Well, now that the manufacturer has refused to repair the inverter, I think you may start removing screws without any consequences. 🙂
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I'm in the business of solar inverters. Our inverters have temperature sensors in the silicone power modules. Good chances the power module was fried and took the temperature sensor with it. Have a look if you see something like this inside of the inverter: flowSOL 0 BI (T) primary | Vincotech
Edit: Faults like this typically are caused by so called insulation/isolation faults where faulty PV modules or cabling create a short to PE. This most of the time instantly kill the power modules with transformerless inverters (as are most pv inverters since several years).
Edit: Faults like this typically are caused by so called insulation/isolation faults where faulty PV modules or cabling create a short to PE. This most of the time instantly kill the power modules with transformerless inverters (as are most pv inverters since several years).
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