Integrated Bi-Directional DC-DC Converter for Current Control in Li-Ion Modular Battery Monoblocks
An apparatus for controlling a battery monoblock charge and discharge current comprising: a battery monoblock having a series stack of battery cells, a battery monoblock controller connected to the series stack of battery cells and connected to a monoblock current sensor, a first battery cell voltage sensor connected to the series stack of battery cells, a second battery cell voltage sensor connected to the series stack of battery cells, and a bi-directional DC/DC converter connected between the series stack of battery cells and the first battery cell voltage sensor and connected to the battery monoblock controller, wherein the bi-directional DC/DC converter controls a charge or a discharge of the battery monoblock.
1 . An apparatus for controlling a battery monoblock charge and discharge current comprising:
a battery monoblock having:
a series stack of battery cells;
a battery monoblock controller connected to the series stack of battery cells and connected to a monoblock current sensor;
a first battery cell voltage sensor connected to the series stack of battery cells;
a second battery cell voltage sensor connected to the series stack of battery cells; and
a bi-directional DC/DC converter connected between the series stack of battery cells and the first battery cell voltage sensor and connected to the battery monoblock controller,
wherein the bi-directional DC/DC converter controls a charge or a discharge of the battery monoblock.
2 . The apparatus of claim 1 , wherein the series stack of battery cells is a high voltage series stack of battery cells.
3 . The apparatus of claim 1 further comprising an internal monoblock contactor or relay connected between the series stack of battery cells and the bi-directional DC/DC converter, and connected to the battery monoblock controller.
4 . The apparatus of claim 1 , wherein a current regulation limit for charging and discharging are independent of one another.
5 . The apparatus of claim 1 , wherein the bi-directional DC/DC converter is configured to convert a sum of a voltage of the series stack of battery cells to a pre-configured, constant monoblock output voltage.
6 . The apparatus of claim 1 , wherein one or more of the apparatus are installed on an aircraft.
7 . The apparatus of claim 6 , wherein the bi-directional DC/DC converter is configured to convert an aircraft bus voltage to a pre-configured charging voltage and apply a constant voltage to the series stack of battery cells for a charging time period.
8 . The apparatus of claim 7 wherein the bi-directional DC/DC converter is configured to limit the current delivered to the series stack of battery cells to no more than a charge regulation set point defined in a battery monoblock controller's software.
9 . A method for controlling a battery monoblock charge and discharge current comprising the steps of:
providing an apparatus including:
a battery monoblock having:
a series stack of battery cells;
a battery monoblock controller connected to the series stack of battery cells and connected to a monoblock current sensor;
a first battery cell voltage sensor connected to the series stack of battery cells;
a second battery cell voltage sensor connected to the series stack of battery cells; and
a bi-directional DC/DC converter connected between the series stack of battery cells and the first battery cell voltage sensor and connected to the battery monoblock controller,
wherein the bi-directional DC/DC converter controls a charge or a discharge of the battery monoblock;
sensing a bus voltage with the monoblock controller;
determining if the bus voltage is higher or lower than a target threshold; and
charging the battery monoblock if the bus voltage is higher than the target threshold or discharging the battery monoblock if the bus voltage is lower than the target threshold.
10 . The method of claim 9 wherein the series stack of battery cells is a high voltage series stack of battery cells.
11 . The method of claim 9 further comprising an internal monoblock contactor or relay connected between the series stack of battery cells and the bi-directional DC/DC converter, and connected to the battery monoblock controller.
12 . The method of claim 9 wherein a current regulation limit for charging and discharging are independent of one another.
13 . The method of claim 9 comprising the bi-directional DC/DC converter converting a sum of a voltage of the series stack of battery cells to a pre-configured, constant monoblock output voltage.
14 . The method of claim 9 wherein one or more of the apparatuses are installed on an aircraft.
15 . The method of claim 14 , comprising the bi-directional DC/DC converter converting an aircraft bus voltage to a pre-configured charging voltage and applying a constant voltage to the series stack of battery cells for a charging time period.
16 . The method of claim 15 comprising the bi-directional DC/DC converter limiting the current delivered to the series stack of battery cells to no more than a charge regulation set point defined in a battery monoblock controller's software.
17 . An apparatus for controlling a battery charge and discharge current comprising:
a battery comprising a plurality of battery monoblocks each having:
a series stack of battery cells;
a battery monoblock controller connected to the series stack of battery cells and connected to a monoblock current sensor;
a first battery cell voltage sensor connected to the series stack of battery cells;
a second battery cell voltage sensor connected to the series stack of battery cells; and
a bi-directional DC/DC converter connected between the series stack of battery cells and the first battery cell voltage sensor and connected to the battery monoblock controller,
wherein the bi-directional DC/DC converter controls a charge or a discharge of the battery monoblock; and
a battery controller configured to control an overall current limit of the battery by independently adjusting a current limit of each monoblock via its battery monoblock controller.
18 . The apparatus of claim 17 wherein a current limit of each of the monoblocks is adjusted to deliver an average load current as requested by the battery controller while the current limit of each monoblock differs as needed.
19 . The apparatus of claim 18 , wherein the average load current requested by the battery controller is delivered by adjusting a current limit based on time, such that the current limit for a first time period is different than for a second time period.
20 . The apparatus of claim 17 , wherein each battery monoblock controller is configured to command a maximum current limit to the dc/dc converter until a voltage threshold of the monoblock is met, followed by a lower current limit.