CHARGING EFFICIENCY USING SELECTABLE ISOLATION
First Claim
1. An apparatus for charging an energy storage system (ESS) from an AC line voltage, comprising:
- a boost stage for converting the AC line voltage to a first ESS charging voltage;
an isolation stage, coupled to the boost stage, for converting the first ESS charging voltage to a second ESS charging voltage with the second ESS charging voltage less than the first ESS charging voltage, the isolation stage removing a common mode current between the ESS and the boost stage;
a configurator, responsive to a control signal, to set a direct communication of the first ESS charging voltage to the ESS in a bypass mode and to open the direct communication of the first ESS charging voltage to the ESS in an isolation mode; and
a controller, coupled to the configurator, for setting the modes responsive to a battery voltage, a peak of the AC line voltage, and a total leakage current at an input of the AC line voltage, the controller asserting the control signal to the configurator.
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Abstract
The apparatus for charging an energy storage system (ESS) from an AC line voltage includes a boost stage for converting the AC line voltage to a first ESS charging voltage; an isolation stage, coupled to the boost stage, for converting the first ESS charging voltage to a second ESS charging voltage with the second ESS charging voltage less than the first ESS charging voltage, the isolation stage removing a common mode current between the ESS and the boost stage; a configurator, responsive to a control signal, to set a direct communication of the first ESS charging voltage to the ESS in a bypass mode and to open the direct communication of the first ESS charging voltage to the ESS in an isolation mode; and a controller, coupled to the configurator, for setting the modes responsive to a battery voltage, a peak of the AC line voltage, and a total leakage current at an input of the AC line voltage, the controller asserting the control signal to the configurator.
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Citations
12 Claims
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1. An apparatus for charging an energy storage system (ESS) from an AC line voltage, comprising:
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a boost stage for converting the AC line voltage to a first ESS charging voltage; an isolation stage, coupled to the boost stage, for converting the first ESS charging voltage to a second ESS charging voltage with the second ESS charging voltage less than the first ESS charging voltage, the isolation stage removing a common mode current between the ESS and the boost stage; a configurator, responsive to a control signal, to set a direct communication of the first ESS charging voltage to the ESS in a bypass mode and to open the direct communication of the first ESS charging voltage to the ESS in an isolation mode; and a controller, coupled to the configurator, for setting the modes responsive to a battery voltage, a peak of the AC line voltage, and a total leakage current at an input of the AC line voltage, the controller asserting the control signal to the configurator. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A method for charging an energy storage system (ESS) from an AC line voltage, the method comprising the steps of:
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a) measuring an AC input voltage for each phase of the AC line voltage; b) calculating an input leakage current responsive to a Y impedance at an input for the AC line voltage; c) calculating an ESS leakage current due to an ESS bus Y impedance to ground; d) testing whether a total leakage current, including a sum of the input leakage current and the ESS leakage current, exceeds a predetermined value; e) testing whether a peak voltage for the AC line voltage exceeds a voltage of the ESS; and f) charging the ESS from the AC line voltage using a non-isolated boost stage resulting from bypassing an isolation stage including a buck conversion function when both the tests at step e) and step f) are negative; and
otherwise;g) charging the ESS from the AC line voltage using both the boost stage and the isolation stage when either the tests at step e) and step f) are affirmative. - View Dependent Claims (11, 12)
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Specification