초록 ▼

Charging time of a capacitor is shortened while avoiding erroneous firing due to distortion of a power supply voltage and sustaining an inrush current at a constant level. In the charge control method of a capacitor in a thyristor converter comprising a thyristor for rectifying an AC voltage, a CPU

Charging time of a capacitor is shortened while avoiding erroneous firing due to distortion of a power supply voltage and sustaining an inrush current at a constant level. In the charge control method of a capacitor in a thyristor converter comprising a thyristor for rectifying an AC voltage, a CPU delivering an on/off control signal to a thyristor driver for driving the thyristor, a voltage detection sensor for measuring the AC voltage and the capacitor charging voltage, and the capacitor connected with a DC circuit, the AC voltage and the capacitor charging voltage are measured by means of the voltage detection sensor, differential voltage between the firing phase voltage of the thyristor and the capacitor charging voltage is determined, and the thyristor is fired only when the firing phase voltage of the thyristor becomes lower than a specified voltage determined from the differential voltage.

대표청구항 ▼

We claim: 1. A charge control method of a capacitor in a thyristor converter equipped with a thyristor for rectifying an AC voltage, a CPU for outputting an on/off control signal to a thyristor driver for driving the thyristor, a voltage detection sensor for measuring the AC voltage and a capacitor

We claim: 1. A charge control method of a capacitor in a thyristor converter equipped with a thyristor for rectifying an AC voltage, a CPU for outputting an on/off control signal to a thyristor driver for driving the thyristor, a voltage detection sensor for measuring the AC voltage and a capacitor charging voltage, and a capacitor connected to a DC circuit, said method comprising the steps of: measuring the AC voltage and the capacitor charging voltage with the voltage detection sensor, and determining a differential voltage between the thyristor firing phase voltage and the capacitor charging voltage, and firing the thyristor only when the firing phase voltage of the thyristor becomes lower than a specified voltage determined from the differential voltage, wherein, if a firing start interval of the thyristor is not shorter than a time calculated by subtracting a predetermined time from the previous firing start interval, the thyristor is fired at one control cycle earlier than the previous firing start timing by subtracting 1 from the previous firing start counter value. 2. A charge control method of a capacitor in a thyristor converter equipped with a thyristor for rectifying an AC voltage, a CPU for outputting an on/off control signal to a thyristor driver for driving the thyristor, a voltage detection sensor for measuring the AC voltage and a capacitor charging voltage, and a capacitor connected to a DC circuit, said method comprising the steps of: measuring the AC voltage and the capacitor charging voltage with the voltage detection sensor, and determining a differential voltage between the thyristor firing phase voltage and the capacitor charging voltage, and firing the thyristor only when the firing phase voltage of the thyristor becomes lower than a specified voltage determined from the differential voltage, wherein a curve a of a capacitor voltage VPN versus a differential voltage ΔVPN in which the line voltage waveform is multiplied by the differential voltage ΔVREQ required to attain a predetermined capacitor voltage and divided by a peak value VPEAK of the line voltage waveform is obtained, wherein a curve b in which the curve a is multiplied by a coefficient in the capacitor direction VPN to compensate a control calculation delay by the CPU is obtained, wherein a curve c in which a voltage ΔVMIN which is necessary and sufficient to charge the capacitor is added to the curve a is obtained, and wherein a curve d in which the curve b is used at an area where the capacitor charging voltage VPN is low and the curve c is used at an area where the capacitor charging voltage is high is obtained. 3. The charge control method of a capacitor in a thyristor converter as recited in claim 2, wherein a ROM in which the curve d as table data is stored is provided.