Some implementations include an apparatus configured to, in a wellbore, eliminate voltage on one or more first conductors that are electrically connected to a surface-based power source. The apparatus may include a shorting ring electrically connectable to the first conductors and configured to electrically short the first conductors upon establishing an electrical connection with the first conductors. The apparatus may include a solenoid assembly to actuate in response to power on the first conductors from the surface-based power source. The apparatus may include a pin slider assembly connected to the first conductors and configured to move, in response to actuation by the solenoid assembly, between an electrical connection with the shorting ring and an electrical connection with one or more second conductors that have an electrical connection with a permanent magnet motor winding in the wellbore.

A power-side shutdown protection method for a power conversion circuit, a power converter, a combiner box, and a power conversion system are provided. The power-side shutdown protection method includes: determining a DC/DC conversion circuit connected to a DC power supply with a reverse current as a target DC/DC conversion circuit, and short circuiting a positive electrode and a negative electrode at a power side of the target DC/DC conversion circuit; controlling a switch connected to the target DC/DC conversion circuit to be turned off; determining whether the switch controlled to be turned off is actually turned off; and stopping short circuiting the positive electrode and the negative electrode at the power side of the target DC/DC conversion circuit in a case that the switch is actually turned off.

A potential generating circuit includes a first output circuit configured to output a first signal, a second output circuit configured to output a second signal different from the first signal, and a control circuit configured to control the first output circuit and the second output circuit to make a signal output from one of the first output circuit and the second output circuit according to a combination of a magnitude relation between a potential of the first signal and a first set potential and a magnitude relation between a potential of the second signal and a second set potential.

A load switch and a power system are provided. The load switch includes a power input terminal, a power output terminal, a voltage-current conversion circuit, a capacitor and a comparator. The power input terminal is configured to receive an input voltage. The power output terminal is configured to provide an output voltage. The voltage-current conversion circuit includes a first input terminal, a second input terminal and a current difference output terminal. The first input terminal and the second input terminal are connected to the power output terminal and the power input terminal, respectively, and configured to receive the output voltage and the input voltage, respectively. A current difference characterizing a voltage difference between the output voltage and the input voltage is output at the current difference output terminal.