Electric vehicle energy storage systems for mitigating transient load conditions in low voltage buses
An energy storage system includes a plurality of batteries coupled in series, a plurality of first isolated DC-DC power converters each having first and second sides, a DC bus coupled to the second sides of the plurality of first isolated DC-DC power converters, and a second isolated DC-DC power converter coupled in parallel with the plurality of first isolated DC-DC power converters. Each of the first sides of the plurality of first isolated DC-DC power converters is coupled to at least one of the batteries. The second isolated DC-DC power converter includes a first side coupled to the plurality of batteries and a second side coupled to the DC bus. The second isolated DC-DC power converter is configured to mitigate a transient load condition on the DC bus.
1 . An energy storage system for an automotive vehicle, the system comprising:
a plurality of batteries coupled in series;
a plurality of first isolated DC-DC power converters configured to operate at a first switching frequency, each of the plurality of first isolated DC-DC power converters having first and second sides, each of the first sides coupled to at least one of the batteries;
a DC bus coupled to the second sides of the plurality of first isolated DC-DC power converters;
a second isolated DC-DC power converter including first and second sides coupled in parallel with the plurality of first isolated DC-DC power converters, the first side of the second isolated DC-DC power converter coupled to the plurality of batteries coupled in series and the second side of the second isolated DC-DC power converter coupled to the DC bus; and
at least one controller coupled to the second isolated DC-DC power converter, the at least one controller configured to:
detect a transient load condition;
in response to detecting the transient load condition, transmit an enable signal to the second isolated DC-DC power converter to cause the second isolated DC-DC power converter to begin operating; and
control the second isolated DC-DC power converter at a second switching frequency greater than the first switching frequency of the plurality of first isolated DC-DC power converters.
2 . The energy storage system of claim 1 , wherein the system does not include a battery module coupled to the second sides of the plurality of first isolated DC-DC power converters.
3 . The energy storage system of claim 2 , wherein the second isolated DC-DC power converter is a bi-directional DC-DC power converter.
4 . The energy storage system of claim 3 , wherein at least one of the plurality of first isolated DC-DC power converters is a bi-directional DC-DC power converter.
5 . The energy storage system of claim 2 , further comprising at least one ultra-capacitor coupled to the DC bus.
6 . The energy storage system of claim 5 , wherein the at least one ultra-capacitor has a capacitance of at least one farad.
7 . The energy storage system of claim 2 , wherein each of the second sides of the plurality of first isolated DC-DC power converters are coupled in parallel.
8 . The energy storage system of claim 1 , wherein a transient response time of the second isolated DC-DC power converter is faster than a transient response time of the plurality of first isolated DC-DC power converters.
9 . The energy storage system of claim 1 , wherein the at least one controller is configured to control at least one isolated DC-DC power converter of the plurality of isolated DC-DC power converters at a switching frequency of 10 MHz or more.
10 . The energy storage system of claim 1 , further comprising at least one ultra-capacitor coupled to the DC bus, the at least one ultra-capacitor having a capacitance of at least one farad.
11 . An energy storage system for an automotive vehicle, the system comprising:
a plurality of batteries coupled in series;
a plurality of isolated DC-DC power converters each having first and second sides, each of the first sides coupled to at least one of the batteries;
a DC bus coupled to the second sides of the plurality of isolated DC-DC power converters;
at least one switching device coupled to the DC bus;
at least one ultra-capacitor coupled to the DC bus and the second sides of the plurality of isolated DC-DC power converters via the at least one switching device; and
at least one controller coupled to the switching device, the at least one controller configured to detect a transient load condition and in response to detecting the transient load condition, transmit an enable signal to the switching device to cause the switching device to begin operating,
wherein:
the at least one ultra-capacitor is configured to mitigate the transient load condition on the DC bus; and
the system does not include a battery module coupled to the second sides of the plurality of isolated DC-DC power converters.
12 . The energy storage system of claim 11 , wherein the at least one ultra-capacitor has a capacitance of at least one farad.
13 . The energy storage system of claim 12 , wherein:
the plurality of isolated DC-DC power converters is a plurality of first isolated DC-DC power converters; and
the system further comprises a second DC-DC power converter coupled in parallel with the at least one ultra-capacitor and including the at least one switching device.
14 . The energy storage system of claim 13 , wherein the second DC-DC power converter is a non-isolated DC-DC power converter.
15 . The energy storage system of claim 12 , wherein each of the second sides of the plurality of isolated DC-DC power converters are coupled in parallel.
16 . The energy storage system of claim 11 , wherein the at least one controller is configured to control at least one isolated DC-DC power converter of the plurality of isolated DC-DC power converters at a switching frequency of 10 MHz or more.
17 . An energy storage system for an automotive vehicle, the system comprising:
a plurality of batteries coupled in series;
a plurality of first isolated DC-DC power converters each having first and second sides, each of the first sides coupled to at least one of the batteries;
a DC bus coupled to the second sides of the plurality of isolated DC-DC power converters;
a second isolated DC-DC power converter including first and second sides coupled in parallel with the plurality of first isolated DC-DC power converters, the first side of the second isolated DC-DC power converter coupled to the plurality of batteries and the second side of the second isolated DC-DC power converter coupled to the DC bus; and
at least one controller coupled to the plurality of first isolated DC-DC power converters and the second isolated DC-DC power converter, the at least one controller configured to:
control at least one isolated DC-DC power converter of the plurality of first isolated DC-DC power converters at a switching frequency of 10 MHz or more to mitigate a transient load condition on the DC bus;
detect the transient load condition; and
in response to detecting the transient load condition, transmit an enable signal to the second isolated DC-DC power converter to cause the second isolated DC-DC power converter to begin operating.
18 . The energy storage system of claim 17 , wherein the system does not include a battery module coupled to the second sides of the plurality of isolated DC-DC power converters.
19 . The energy storage system of claim 17 , wherein each of the second sides of the plurality of isolated DC-DC power converters are coupled in parallel.
20 . The energy storage system of claim 17 , wherein the second isolated DC-DC power converter is a bi-directional DC-DC power converter.