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 switching system, 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 switching system, 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 switching system;
wherein a residual-current device (RCD) trip level is associated with a source for the AC input voltage and wherein the controller asserts the control signal to set the bypass mode when both the battery voltage is above the peak of the AC line and the leakage current is below the RCD trip level.
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Accused Products
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
10 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 switching system, 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 switching system, 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 switching system; wherein a residual-current device (RCD) trip level is associated with a source for the AC input voltage and wherein the controller asserts the control signal to set the bypass mode when both the battery voltage is above the peak of the AC line and the leakage current is below the RCD trip level. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. 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 d) and step e) 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 (9, 10)
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Specification