System and method for charging a capacitor used to power measurement-while-drilling equipment

摘要

A system for charging a capacitor used to power measurement-while-drilling equipment includes a power bus, which is electrically connected to the capacitor; a first pair of battery terminals; switching circuitry for electrically connecting the power bus to and disconnecting the power bus from the first pair of battery terminals; and a controller, for controlling the switching circuitry, which is configured to charge the capacitor by applying a first pulse width modulated control signal to control the switching circuitry. The first pulse width modulated control signal has a duty cycle selected such that the voltage of the first battery remains above a first minimum operating voltage while the capacitor is being charged.

主权项

1. A system for charging a capacitor used to power measurement-while-drilling equipment, the system comprising:
(a) a power bus and the capacitor, wherein the capacitor is electrically connected to the power bus and wherein the measurement-while-drilling equipment is electrically connected to the power bus when powered by the capacitor; (b) a first pair of battery terminals for connecting to a first battery; (c) a second pair of battery terminals for connecting to a second battery and electrically connected in parallel to the first pair of battery terminals; (d) first switching circuitry operable in a closed state to electrically connect the power bus to the first pair of battery terminals and in an open state to disconnect the power bus from the first pair of battery terminals, and second switching circuitry operable in a closed state to electrically connect the power bus to the second pair of battery terminals and in an open state to disconnect the power bus from the second pair of battery terminals independently from the first pair of battery terminals; and (e) a controller configured to alternate between:
(i) only charging the capacitor using the first battery by electrically connecting the first pair of battery terminals to the power bus by operating the first switching circuitry in the closed state and electrically disconnecting the second pair of battery terminals from the power bus by operating the second switching circuitry in the open state, wherein durations for which the power bus is connected to the first pair of battery terminals are selected such that the voltage of the first battery remains above a first minimum operating voltage while the capacitor is being charged by the first battery; and(ii) only charging the capacitor using the second battery by electrically connecting the second pair of battery terminals to the power bus by operating the second switching circuitry in the closed state and electrically disconnecting the first pair of battery terminals from the power bus by operating the first switching circuitry in the open state, wherein durations for which the power bus is connected to the second pair of battery terminals are selected such that the voltage of the second battery remains above a second minimum operating voltage while the capacitor is being charged by the second battery.