IR2153 smps with short circuit protection.
- Thread starter norazmi
- Start date
Bettecher, for your calculations here, are they for a full bridge you were talking about earlier or for a half bridge you posted the schematic for a little later in thread.
wally7856,
I’m sure that all calculations were done to half bridge as follow.
X = 8 ' Use (8) for Half Bridge or (4) for Full Bridge
Np = (Vmax * 10 ^ 8) / (X * F * B * Ae)
Ns = (1.1 * Vout * Np) / (Vmin * 0.5)
Regards
Marcos Bettecher
Bettecher,
I have been studying how to make switching power supplies and i always try to check my calculations with others when enough information is given. The only information that you left out was the ferrite material used in your EE42/21/20 core. This makes it hard to confirm the best flux level, but since you gave the flux level you used i could still calculate the primary turns.
Please take a look at my work and compare it to yours. I belive you should have used about 33 primary turns and you used 16 turns.
Np = (Vmax * 10 ^ 8) / (X * F * B * Ae)
The constant X used in the primary turns formula can be any of the following.
1.11 - compensates for the sine wave ratio of RMS to average voltage. Used for standard sine wave transformer design.
1 - Used for half wave square wave operation of a transformer. A flyback converter uses this constant.
2 - This is the square wave constant above multiplied by 2. there are two semi cycles in each full cycle (Hertz refers to full cycles). A half bridge uses this constant.
4 - This is the constant 2 above multiplied by two for topographies that have a flux swing in all 4 quadrants, like a full bridge circuit.
These are the only constants there are for this formula.
UNITS IN FORMULA
Ae = Area of center leg of transformer in CM squared
B = Flux in Gauss, common values of 1400 to 1600
F = Frequency the transformer is switched at in Hz
Vmax = Voltage in volts the transformer sees
GENERAL RULES
For a half bridge driven off of a split capacitor supply the transformer only sees half of the bus voltage.
Vpri minV gives you the minimum turns to use on the primary, this sets the flux number you used in the original calculations as a minimum. As the voltage rises to Vpri maxV the flux rises, possibly to the point of saturation, if you started to high in flux density to begin with.
Vpri maxV gives you the maximum turns to use on the primary, this limits the flux to a maximum of your original number used in the formula. The flux will go down when the voltage goes to Vpri minV. This will make a safe design.
Increasing the Gauss decreases the turns.
As the turns go down the Gauss goes up
NUMBERS TO USE FOR YOUR DESIGN
Ae = 2.4 CM squared
B = 1500 Gauss
The constant 2 as defined above
Frequency 80,000 Hz
Vmax, from schematic, 380Vdc bus / 2 for driving transformer with split capacitor power supply = 190Vdc
Np = (Vmax * 10 ^ 8) / (X * F * B * Ae)
Np = 190Vdc * 100,000,000 / 2 * 80,000Hz * 1500G * 2.4CM squared
Np = 19,000,000,000 / 576,000,000
Np = 32.986 = 33 turns.
Your calculations showed 16 turns. So if i am right you are actually running 3000 Gauss on your transformer.
Let me know what you think.
Wally
I have been studying how to make switching power supplies and i always try to check my calculations with others when enough information is given. The only information that you left out was the ferrite material used in your EE42/21/20 core. This makes it hard to confirm the best flux level, but since you gave the flux level you used i could still calculate the primary turns.
Please take a look at my work and compare it to yours. I belive you should have used about 33 primary turns and you used 16 turns.
Np = (Vmax * 10 ^ 8) / (X * F * B * Ae)
The constant X used in the primary turns formula can be any of the following.
1.11 - compensates for the sine wave ratio of RMS to average voltage. Used for standard sine wave transformer design.
1 - Used for half wave square wave operation of a transformer. A flyback converter uses this constant.
2 - This is the square wave constant above multiplied by 2. there are two semi cycles in each full cycle (Hertz refers to full cycles). A half bridge uses this constant.
4 - This is the constant 2 above multiplied by two for topographies that have a flux swing in all 4 quadrants, like a full bridge circuit.
These are the only constants there are for this formula.
UNITS IN FORMULA
Ae = Area of center leg of transformer in CM squared
B = Flux in Gauss, common values of 1400 to 1600
F = Frequency the transformer is switched at in Hz
Vmax = Voltage in volts the transformer sees
GENERAL RULES
For a half bridge driven off of a split capacitor supply the transformer only sees half of the bus voltage.
Vpri minV gives you the minimum turns to use on the primary, this sets the flux number you used in the original calculations as a minimum. As the voltage rises to Vpri maxV the flux rises, possibly to the point of saturation, if you started to high in flux density to begin with.
Vpri maxV gives you the maximum turns to use on the primary, this limits the flux to a maximum of your original number used in the formula. The flux will go down when the voltage goes to Vpri minV. This will make a safe design.
Increasing the Gauss decreases the turns.
As the turns go down the Gauss goes up
NUMBERS TO USE FOR YOUR DESIGN
Ae = 2.4 CM squared
B = 1500 Gauss
The constant 2 as defined above
Frequency 80,000 Hz
Vmax, from schematic, 380Vdc bus / 2 for driving transformer with split capacitor power supply = 190Vdc
Np = (Vmax * 10 ^ 8) / (X * F * B * Ae)
Np = 190Vdc * 100,000,000 / 2 * 80,000Hz * 1500G * 2.4CM squared
Np = 19,000,000,000 / 576,000,000
Np = 32.986 = 33 turns.
Your calculations showed 16 turns. So if i am right you are actually running 3000 Gauss on your transformer.
Let me know what you think.
Wally
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I never said that you are wrong!
I have just used the formula, and it gave me that number!
Sorry
OK guys, I found my mistake. In this particular topology used by Bettecher, it turns out that the flux does swing in all 4 quadrants even though it is a half bridge. Therefore this will multiply the flux x 2 because it swings through zero flux both ways 1500Gauss, for a total of 3000 Gauss.
I found this out by looking in Keith Billings book Switchmode Power Supply Handbook, Chapter 12, Half bridge Push-Pull Duty Ratio Controlled Converters. The exact same power circuit Bettecher used is in there with an explanation of how it works with an example calculating transformer turns.
So in the formula above in my calculations i should have used the 4 constant and not the 2 constant.
I found this out by looking in Keith Billings book Switchmode Power Supply Handbook, Chapter 12, Half bridge Push-Pull Duty Ratio Controlled Converters. The exact same power circuit Bettecher used is in there with an explanation of how it works with an example calculating transformer turns.
So in the formula above in my calculations i should have used the 4 constant and not the 2 constant.
Good, Wally, if u already made this smps please share with us. Any additional idea is welcome
I have not made anything yet. I am still studying.
hi guys . i've finally completed the pcb of the smps . i chose ir2110 because it has protection features and here where i am they both are sold at the same price as ir2153 . i like the protection because if the amp gets over loaded or the amp transistor fails the power supply will switch itself off hopefully
. i like the protection because if the amp gets over loaded or the amp transistor fails the power supply will switch itself off hopefully
Last edited:
Hi guys, sorry for the delay. I got a health problem (sinusitis). Now I'm fine.
Ok, I had the same doubts in the past and I had to make a compilation of various formulas in order to choose the best ones. After to read some books like:
Transformer and inductor design - Colonel W.M. T. Mclyman
Switching Power Supply Design Third Edition - Abraham I. Pressman
Power Supply Cookbook 2E - Marty Brown
And others from my country, I finally found some workable equations and was possible to make some successfully smps designs.
I’d like to say thanks to everybody for the help and the comments what are extremely welcome. I’m here to learn and share.
Regards
Marcos Bettecher
Ok, I had the same doubts in the past and I had to make a compilation of various formulas in order to choose the best ones. After to read some books like:
Transformer and inductor design - Colonel W.M. T. Mclyman
Switching Power Supply Design Third Edition - Abraham I. Pressman
Power Supply Cookbook 2E - Marty Brown
And others from my country, I finally found some workable equations and was possible to make some successfully smps designs.
I’d like to say thanks to everybody for the help and the comments what are extremely welcome. I’m here to learn and share.
Regards
Marcos Bettecher
hi guys . i've finally completed the pcb of the smps . i chose ir2110 because it has protection features and here where i am they both are sold at the same price as ir2153
Stewin,
By looking your schematic I found some errors.
Please, consider to make some changes:
1. LED2 needs to be inverted.
2. LED3 needs to be inverted.
3. R9 - 2k2. Better 4k7
4. R24 - 33K – the valor should be increased for 80 + 80 volts. ( the original design was 50 + 50).
5. Minimal load resistor not found.
6. Output filter – Inductors not found.( don’t forget!)
Regards
Marcos Bettecher