Two question of Resonant Switched Capacitor Active cell balancing

[iamkim]

Hello! Good day.

I have created an active cell balancing circuit using a resonant switched capacitor. I determined that the voltage applied to the MOSFETs was insufficient, so I used a level shifter circuit to amplify the 5V PWM frequency output from the Arduino to 11.1V to proceed with balancing. However, I observed heating and melting of the breadboard at MOSFETs connected to the middle cells, specifically at MOSFETs 3 and 4. I am unsure why the MOSFETs are overheating. During balancing, I connected three batteries in series: a 4.01V battery, a 3.895V battery, and a 3.855V battery. While balancing, I observed these heating issues, and suspect that the voltage applied to the MOSFETs is insufficient. I tried increasing the amplification circuit voltage to 18V by adjusting the power supply to 18V, setting the base resistor to 10kΩ and the collector resistor to 1kΩ. However, I measured only 7V, which is far from the expected value. Why am I measuring only 7V? I am using a PNP transistor ST2N3906. In summary, I would like to know why MOSFETs 3 and 4 in the balancing circuit are overheating, and why only 7V is measured when applying 18V in the amplification circuit. Thank you!

 

[D.A.(Tony)Stewart]

You are using positive voltages and currents on PNPs. Why?
Zip your .asc file if you want more help.

How will avoid both FETs conducting at the same time? (shootthru). There must be a finite dead-time to transfer the charge with both FETs off.

 

[BradtheRad]

I've tried to simulate triple-connected battery chargers. I observe two batteries in series generate high volt levels greater than the supply. The series voltage creates rogue current flows. Ampere levels are extreme. It happens at odd times when certain mosfets permit conduction.

It does not happen using 6 NPN bjt's. With a lot of experimenting I found these need bias signals that go into negative polarity, and bias resistors limiting current flow. Mistakes are easy. Mistakes are risky with Li-ion cells.

18V switched On-and-Off rapidly doesn't not read as 18V. Reading with a plain averaging meter it reads as a lower voltage.