Latch current limiter circuit for spacecraft and spacecraft power system using the same

A spacecraft power system, for providing at least an operational power voltage of an aerospace equipment, wherein the spacecraft power system comprises:

• a power supply unit, comprising a power output terminal for providing the operational power voltage;
• and
• a latch current limiter circuit, comprising:
• an input terminal, coupled to the output terminal of the power supply unit;
• an output terminal;
• a current sensing circuit, coupled between the input terminal and the output terminal, for outputting a current sense voltage according to the current flowing from the input terminal to the output terminal;
• a transistor switch circuit, comprising a first terminal, a second terminal and a control terminal, wherein the first terminal of the transistor switch circuit is coupled to the input terminal through a current sensing circuit, and the second terminal of the transistor switch circuit is coupled to the output terminal;
• a transistor switch control circuit, comprising:
• a transformer, comprising a primary side coil and a secondary side coil;
• an LC resonant circuit, coupled to the primary side coil of the transformer;
• and
• a rectifier filtering circuit, comprising a first input terminal, a second input terminal, a first output terminal and a second output terminal, wherein the first input terminal of the rectifier filtering circuit is coupled to a first terminal of the secondary side coil, the second input terminal of the rectifier filtering circuit is coupled to a second terminal of the secondary side coil, the first output terminal of the rectifier filtering circuit is coupled to the control terminal of the transistor switch circuit, and the second output terminal of the rectifier filtering circuit is coupled to the second terminal of the transistor switch circuit;
• a switching circuit, comprising an input terminal and an output terminal, wherein the output terminal of the switching circuit is coupled to the LC resonant circuit;
• and
• a relaxation oscillator circuit, receiving the current sense voltage, outputting a clock signal to the input terminal of the switching circuit, for controlling the switching circuit, to control an output voltage of the transistor switch control circuit, such that an operation mode of the transistor switch circuit is controlled,
• wherein the relaxation oscillator circuit comprises a variable-capacitance circuit for changing the capacitance value of the variable-capacitance circuit according to the current sense voltage,
• wherein the relaxation oscillator circuit is for changing a frequency of the clock signal output from the relaxation oscillator circuit according to the capacitance value of the variable-capacitance circuit, and
• wherein, when the current flowing from the input terminal to the output terminal is greater than a preset value, the current sense voltage is changed so as to change the capacitance value of the variable-capacitance circuit, and the frequency of the clock signal is changed such that an operation of the transistor switch control circuit deviates from a resonance point, thereby reducing the output voltage of the transistor switch control circuit, causing the transistor switch circuit to operate in a resistance mode to limit the current from the input terminal to the output terminal.