The PFC Charger and DC/DC Converter are both enclosed in a single splashproof aluminum case. The PFC Charger is completely isolated and has 1200W output charge capability and is configured at the factory. It also receives signals from the BATMON boards to change the charging voltage at the battery pack from Charge to Float output voltage. While it may be noted the battery pack would become imbalanced due to a low power 24V tap for the Power Center, the rebalancing activity during the charge mode refreshes each battery as it reaches the charge limit imposed by the individual BATMON board placed on each battery. Any battery that is reaches the charged voltage sooner is then placed on a dissipative limit so the battery is not overcharged or overvoltaged. The current is then diverted to the batteries that are not at the BATMON limit. Once all batteries have reached the imposed voltage limit based on the BATMON boards, the charger then switches to Float mode for a period of 20-30 seconds. The Charge cycle is then restarted, and the cycle repeats until AC power is removed. This ensures all batteries are charged fully regardless of the imbalance incurred. If a battery becomes overly discharged for any reason, the BATMON board then imposes a power limit at the Power Center, reducing the chance of internal damage to any battery in the string due to a reversed cell. Thus the charging process is focused on proper feeding of the batteries while the BATMON boards watch over each battery individually during the charge and discharge process. Power dissipation at the BATMON boards is also reduced due to the cyclic nature of this charge methodology.
The DC/DC section is completely isolated and capable of 13.5V @ >50A output. The DC/DC section is enabled by an optocoupler signal from the VEHINT circuit during powerup, remotely turning on the DC-DC converter. It is fully off when the DC Enable is not powered. System protection is provided by external fuses.
Due to the large heatsink area, a cooling fan is only needed for charging. A 120VAC fan suits this purpose well. |
