P
P E Schoen
- Jan 1, 1970
- 0
There is a thread in
http://www.diyelectriccar.com/forums/showthread.php/evnetics-developing-dc-dc-converter-72862p5.html
which suggests a half-bridge DC-DC converter with the following topology:
http://www.diodes.com/zetex/?ztx=3.0/application@app~49!top~5!curr~13
Originally I thought it was only useful for low power applications like
phone chargers, and I think the capacitor in series with the primary is
superfluous because of the two series capacitors across the DC bus. I found
a similar topology here:
http://www.st.com/internet/com/TECH...AL_LITERATURE/APPLICATION_NOTE/CD00003910.pdf
I modeled the converter using LTSpice and it seems to work quite well with
reasonable components, and it seems to have less problem with transients
than my direct drive push-pull topology. It also seems to be fairly tolerant
of imbalance and it does allow the use of PWM, although it works best at
50%.
http://www.enginuitysystems.com/pix/Half_Bridge_144V-12V.png
The simulation ASC file is there also:
http://www.enginuitysystems.com/pix/Half_Bridge_144V-12V.asc
In this case, it is a high power step-down DC-DC converter. Apparently many
EVs use a separate 12V battery for accessories so they can use the same
components as wiring as the original ICE donor (or transplant recipient)
car. The 144V is typical for a battery pack and the DC-DC converter uses
power from that to keep the battery charged and run the lights, fans,
wipers, and other usual accessories. But apparently some of the commercially
available converters are not very reliable or efficient, and just using an
ordinary switching supply and/or charger such as are available from
Mean-Well are prone to failure in an automotive environment.
I may try a similar design for my purposes, which is essentially the
reverse. I want to use 24-48 VDC from batteries and boost it to 320 VDC or
640 VDC for a VFD and three-phase motor. I have the previous push-pull
design modified with a capacitor precharge circuit and adjustable PWM but it
has become complicated, and this topology seems simpler and perhaps better.
There seem to be many more drive ICs and complete controllers for
half-bridge than for push-pull, so maybe it's the way to go.
Thanks,
Paul
http://www.diyelectriccar.com/forums/showthread.php/evnetics-developing-dc-dc-converter-72862p5.html
which suggests a half-bridge DC-DC converter with the following topology:
http://www.diodes.com/zetex/?ztx=3.0/application@app~49!top~5!curr~13
Originally I thought it was only useful for low power applications like
phone chargers, and I think the capacitor in series with the primary is
superfluous because of the two series capacitors across the DC bus. I found
a similar topology here:
http://www.st.com/internet/com/TECH...AL_LITERATURE/APPLICATION_NOTE/CD00003910.pdf
I modeled the converter using LTSpice and it seems to work quite well with
reasonable components, and it seems to have less problem with transients
than my direct drive push-pull topology. It also seems to be fairly tolerant
of imbalance and it does allow the use of PWM, although it works best at
50%.
http://www.enginuitysystems.com/pix/Half_Bridge_144V-12V.png
The simulation ASC file is there also:
http://www.enginuitysystems.com/pix/Half_Bridge_144V-12V.asc
In this case, it is a high power step-down DC-DC converter. Apparently many
EVs use a separate 12V battery for accessories so they can use the same
components as wiring as the original ICE donor (or transplant recipient)
car. The 144V is typical for a battery pack and the DC-DC converter uses
power from that to keep the battery charged and run the lights, fans,
wipers, and other usual accessories. But apparently some of the commercially
available converters are not very reliable or efficient, and just using an
ordinary switching supply and/or charger such as are available from
Mean-Well are prone to failure in an automotive environment.
I may try a similar design for my purposes, which is essentially the
reverse. I want to use 24-48 VDC from batteries and boost it to 320 VDC or
640 VDC for a VFD and three-phase motor. I have the previous push-pull
design modified with a capacitor precharge circuit and adjustable PWM but it
has become complicated, and this topology seems simpler and perhaps better.
There seem to be many more drive ICs and complete controllers for
half-bridge than for push-pull, so maybe it's the way to go.
Thanks,
Paul