Coulomb Posted February 19 Share Posted February 19 On 2024/02/18 at 6:22 AM, Scorp007 said: A normal temp is so hot that you cannot keep your finger there longer than 1sec. Not that it is just hot when you touch it. OK, but that would be with a substantial load, right? @wael_fathe mentioned a load of 100 W, for a 5000 W inverter (2% of rated load). Quote Link to comment Share on other sites More sharing options...
Scorp007 Posted February 19 Share Posted February 19 (edited) 46 minutes ago, Coulomb said: OK, but that would be with a substantial load, right? @wael_fathe mentioned a load of 100 W, for a 5000 W inverter (2% of rated load). Point taken. Could it not be like on FETs that are just partially on that they have to absorb a lot of power and heat up. At high current much lower heat. Not a fundi with electronics but observations. Example off a voltage regulator even at low power. We have many thousands of these PSU in the field. Red dot on the basic aluminium heat sink Edited February 19 by Scorp007 Quote Link to comment Share on other sites More sharing options...
wael_fathe Posted March 1 Share Posted March 1 its abit warmer than usual...i gave back to customer it works fine for 10 days..so far so good Quote Link to comment Share on other sites More sharing options...
wael_fathe Posted March 4 Share Posted March 4 On 2023/08/13 at 4:26 PM, BritishRacingGreen said: input. So you will have to clip on about a 12R 10W resistor on the -12V load output to draw at least a 1A current , then check the output voltage. Ideally an oscilloscope on the C116 should be used to check the ripple as well. How much voltage drop is legal after the application of this load ...from 12- to-11.5 is still good? Quote Link to comment Share on other sites More sharing options...
wael_fathe Posted March 4 Share Posted March 4 On 2023/09/02 at 5:22 PM, BritishRacingGreen said: a Short Guide to Bring Up a 5kW Axpert Main Board in the Softest Possible Manner : Chapter 3 Part 1 ---- Testing the DC-DC converter ---- So at this stage we have powered the main board rail supplies via an external PSU feed , without any supply on the battery terminals , and we have no DSP controller card inserted. This is ideal in order to test all the various driver signals without having any power on the mosfets and igbts. Of course it is essential that you test both the battery bus and the high voltage bus for a short circuit. if there are short circuits it is most probably due to a failed igbt or mosfet. You will have to unsolder those devices that causes the short. Below you will find a block diagram of the dc-dc converter : This diagram will help you to understand the working of the dc-dc converter. It is a bidirectional converter and power may flow from either BAT to BUS or vice versa. When the inverter is in battery mode , the power flows from the BAT to the BUS . When the grid or pv is charging the battery , power flows from BUS to BAT . On either side of the high frequency transformer TX1 there is two full bridges, on the BAT side low voltage mosfets are used , and on the BUS side high voltage igbt's are used. Both full bridges are controlled by a two phase PWM controller of type 3525. In our case the 3525 does not vary PWM and therefore the duty cycle is fixed at about 50%. The frequency is about 38khz. The phase A and phase B is 180 degrees out of phase . The output signals can be enabled or disabled by the DSP via the shutdown control pin as shown. So your first question might be : how does the DSP control the direction of power flow . The answer is it does not have to. The answer lies in theory of supply and demand. When there is 50V battery voltage and 0V bus voltage , then power will automatically flow from left to right. The left hand side full bridge will chop the battery dc to ac thru TX1 and the ac produced on the right hand side of TX1 will be full wave rectified by the igbt full bridge. Notice that the transformer ratio of TX1 is 1:8 , meaning the BUS will be about 8 x that of BAT voltage , this will relate to 50V:400V , make sense doesn't it . 400V is what we need on the bus for the DC-AC converter. If the ratio between BAT and BUS are balanced ,Vbus = 8 x Vbat, then no power will flow anymore. If there exists an alternative BUS source , e.g. pv or grid , and Vbat goes lower than Vbus/8 , then guess what , power now flow from right to left. The igbt's now chop dc to ac for TX1 , and the mosfets on the battery side are now merely full wave rectifier. When I started to play with this in practice , I realized this is some kind of magic ! So this is my methodology for bringing up a DC-DC converter that had experienced a catastrophic failure. We going to first debug the driver circuits in a complete zone of comfort , no supplies on the BAT or BUS. Then we going to replace faulty mosfets and igbts. And lastly we are going to manually enable the 3525 PWM , supply a very low BAT supply of 3V (yes 3 volts!) and measure to see if we get 3x8 = 24V on the BUS side. Conversely , we going to inject 24V on the BUS side and check wether we get 3V on the BAT terminals ! . The promise is that we can now test the switching levels not only on the gates , but also between source and drain of the mosfets , and between emitter and collectors of the IGBT's . And if we getting satisfied , we up the 3V to 6V to 9v to 12V and so forth. This is all about bringing up failed sections in the softest possible manner . So in Part 2 I will provide details on how to bring of the drivers for phases A and B , and how to stimulate the 3525 PWN controller to deliver the sources of the driver signals. Also we will monitor the voltage ranges of the gate drivers as not to exceed maximum values. I will provide nice schematics of the drivers in order to help you with the debugging. In Part 3 we will power the chain as mentioned , and test the switching actions of the power devices. So watch out for Part 2 of this chapter 3. NOTE : as explained, the dc-dc converter is merely a simple open loop converter . It is not a voltage or current regulator . The rule of engagement is simple , if the BAT voltage is ratio-metrically higher than that of the BUS , power flows from BAT to BUS. If the BUS voltage is ratio-metrically higher than that of BAT , power flows from BUS to BAT. The ratio of TX1 is fixed at very close to 1:8 . So how do we control battery charge voltage and current? This is done upstream in the BUS circuit by a simple BUCK converter. Therefore the BUCK converter can control the BUS voltage on the left hand side of the bus , thereby regulating the final battery voltage and current. Great explanations the entire process is natural ...only after h bridge ac phase have to be adjusted to suck utility ac in if the battery low and bus high or to spit ac out if battery high bus is low Quote Link to comment Share on other sites More sharing options...
wael_fathe Posted March 4 Share Posted March 4 (edited) On 2023/03/20 at 11:08 AM, BritishRacingGreen said: The inverters that has so called batteryless mode, can be powered by both grid input and/or pv in the absense of battery power. On the MAX family there is only battery supply for the SMPS on the main board. But in addition to this there is a seperate SPS module. This module features two switch mode power supplies, one for grid input and one for MPPT. The resultant isolated 60VDC outputs are wired-or and connected to the main board where it is wired-or again with the battery 48v dc. I am not sure how this is accomplished on the MKS3 and MKS4, maybe on the large flat MPPT board, but thats just a wild guess. EDIT : the pv path does not require the activation via on/off button, it will bring the machine up regardlessly, of course given enough pv power to do so. This has the disadvantage of early morning sunrise chatter of the relays/power supply. But then again I dont think people are using the machine in pv only mode, as a single power source. As short as possible for new comers ...its eaither way The oring happens at the battery side where all 3 sps(mppt sps..ac sps..main sps) ored there so that they operate main sps without on command Though that bit strange as it seems that main sps should always work yet its not if on_off switch in off position...maybe the onnoff switch is used to cut dc for the mains sps whilhe other sps are fed directly with no swicths or any restrictions Or 3 sps (battery sps .ac sps..main sps)..this one i have seen alot in clone models...battery sps is stupid sps that produce 120vdc or so to operate the main sps oring happens there at the output of the battery sps where mppt not need an sps they derive some volt from working controller or panels battery sps work by main switch...mppt and ac sps inject power directly at battery sps forcing main sps to work .... Edited March 4 by wael_fathe Quote Link to comment Share on other sites More sharing options...
Coulomb Posted March 5 Share Posted March 5 23 hours ago, wael_fathe said: How much voltage drop is legal after the application of this load ...from 12- to-11.5 is still good? I would say it's just OK. Voltage regulators usually have a 5% tolerance; 95% x 12 V = 11.4 V. But if there is significant ripple on the output, then it's no good. For example, if the 11.5 V is basically a sawtooth from -12 V to -11 V, then the electrolytic is bad, or maybe 1 A of load is too much. Quote Link to comment Share on other sites More sharing options...
wael_fathe Posted March 13 Share Posted March 13 (edited) this qmax solar inverter is strangely designed first it is compact with some vertical boards for ac ignt output drivers and vertical board for sps and soft start sps second with the ac output igbts removed it should give error 53 soFtstarting ac failed with output ac igbts removed it gave error 58 which is low ac output ac suddenly raise to 230 no raising in soft start fashion the breif is that some units have fewer codes available(no error53 in this one) and fewer fucntions missing(ac not raise gradually) they ALSO INSANELY INSTALL 6 fets there 10 places but they ommit 4 of them however after i fix it i install the missing fets along with thier missing drive componenets Edited March 17 by wael_fathe Quote Link to comment Share on other sites More sharing options...
Coulomb Posted May 5 Share Posted May 5 (edited) On 2022/11/09 at 4:22 AM, BritishRacingGreen said: and the igbt driver section schematic : I see that you have made the same mistake Maxo and I did with R158, R10, and R21. They are marked 18C, which sounds like 18k as you have marked, but in fact it's the code for 15k. I've fixed Maxo's schematic this morning. I doubt it makes a heap of difference, but it did cause at least one reader to be confused about what value to use. Edited May 5 by Coulomb BritishRacingGreen 1 Quote Link to comment Share on other sites More sharing options...
BritishRacingGreen Posted May 6 Author Share Posted May 6 On 2024/05/05 at 6:04 AM, Coulomb said: I see that you have made the same mistake Maxo and I did with R158, R10, and R21. They are marked 18C, which sounds like 18k as you have marked, but in fact it's the code for 15k. I've fixed Maxo's schematic this morning. I doubt it makes a heap of difference, but it did cause at least one reader to be confused about what value to use. thanks @Coulomb , noted. One question I have , is what is the main purpose of that resistor. Not shown in your snippet of schematic is the two electrolytic capacitors, one in parallel with the resistor and one in parallel with the 5v6 zener. The zener tells me that it clamps the bottom cap to 5.6v and the balance of the supply appears across the top cap. The only explanation I can think of is maybe the resistor bleeds off spikes on the supply , especially when the load impedances (the igbt driver) is high. But this is a shot in the dark. Quote Link to comment Share on other sites More sharing options...
Coulomb Posted May 7 Share Posted May 7 10 hours ago, BritishRacingGreen said: what is the main purpose of that resistor. The resistor and zener form a voltage divider; the zener adjusts its resistance so that there is about 5.6 V across it. Without the resistor to push current into the zener and other parts of the circuit, there would be no voltage across the zener, I think. Quote Link to comment Share on other sites More sharing options...
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