Abstract: The present invention relates to a variable voltage regulating device for modulating output voltage, comprising the implementation means of duty cycle modulation and control signal modulation. The duty cycle modulation mechanism entails the use of pulse signals with different duty cycles to produce different voltage signals in the resistor-capacitor network, which are regulated to obtain a control voltage. The original output voltage is then modulated by the control signal and the resistor network based on the Kirchhoff's current law to produce a new output voltage. The control signal modulation mechanism uses the field effect transistor switch to control the resistor network and then uses the resistor network and the Kirchhoff's current law to modulate the original output voltage and deliver a new output voltage.

Abstract: A capacitance fuel volume measuring apparatus for a fuel cell is disclosed. The apparatus utilizes two electrode boards disposed in a fuel tank and an elastic element to perform calculation of the fuel volume in the fuel tank. The apparatus includes a structure disposed in the fuel tank and a control unit. The structure in the fuel tank includes two electrode boards and an elastic element, which maintains the liquid level of the fuel in a level and transmits essential data corresponding to the distance between the two electrode boards to the control unit for calculation such that the control unit may obtain the volume of the fuel in the fuel tank.

Abstract: A fluid measuring device for use in a fluid storage tank, comprising a logic operation unit, a capacitive sensor, and a capacitance sensing circuit; wherein the capacitance sensing circuit is driven by the constant current input to perform the detection of the capacitance value of the capacitive sensor, then perform the conversion from the capacitance value into the signal on the physical characteristics of the fluid body by the logic operation unit. The signal on the physical characteristics can include any of the concentration, density, and surface level of the fluid body. Furthermore, the capacitive sensor can further comprise a reference capacitor and a detection capacitor for detecting the fluid, the latter capacitance is obtained from a differential circuit of the capacitance sensing circuit.

Abstract: The present invention relates to a fuel cell system with series-parallel circuit, comprising a plurality of fuel cell stacks and a series-parallel circuit unit. Each fuel cell stack contains. DC power output terminals, and the series-parallel circuit unit consists of a plurality of parallel mode selection units and DC power output terminals. The DC power output terminal of respective fuel cell stack is electrically connected to the corresponding parallel mode selection unit in the series-parallel circuit unit. The parallel mode selection units are electrically parallel-connected to the DC power output terminal of the series-parallel circuit unit. The parallel mode selection unit selects whether the DC power output terminal of the corresponding fuel cell stack and the DC power output terminal of the series-parallel circuit unit are electrically connected or disconnected.