JPS5840439B2 - Compensation circuit for shaft drive generator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a compensation circuit that compensates for the conversion efficiency of a semiconductor converter that decreases due to an increase in the frequency of an alternator in a shaft-driven power generator.

As a way to save energy on ships, the propeller motor drives an alternating current generator, and its output, which fluctuates in frequency, is converted into high-quality electricity with a constant frequency and constant voltage using a semiconductor conversion circuit, which is then supplied to the ship. There is a so-called shaft-driven power generator.

An object of the present invention is to compensate for the decrease in conversion efficiency of a semiconductor conversion circuit by modifying an automatic voltage regulation circuit (hereinafter referred to as AVR) of an alternator driven by a prime mover whose rotational speed varies.

Hereinafter, a conventional example of the above-mentioned shaft-driven power generator will be described. 1 is an electric motor for driving the propeller 1, 2 is an alternating current generator driven by the prime mover 1 directly or through gears, 2a is its field circuit, 3 is an AVR for the alternating current generator 2; 4 is a semiconductor converter which may be composed of a diode; 5 is a direct actuator; 6 is a separately excited inverter; 7 is a rotating capacitor that supplies current to the separately excited inverter 6; 7a is the field circuit of the rotating capacitor 1, and 8 is the AV for the rotating capacitor 7.
R19 is a breaker for supplying power to the load.

Briefly describing the operation of this shaft-driven power generator, the voltage generated by the alternator 2 is constant because of the AVR 3, but its frequency varies depending on the prime mover.

Therefore, since it cannot be used as is, converter 4
The voltage of the rotary capacitor 7 is used to convert the output into a DC output, and the voltage of the rotating capacitor 7 is used to convert the output into an AC output using a radio wave commutating inverter, that is, a separately excited inverter 6.

In this case, the output voltage of the inverter 6 is the rotating capacitor 7
The voltage becomes constant due to the AVR 8, and as for its frequency, when the output voltage of the converter 4 is increased (if the converter 4 has a diode configuration, the output voltage of the alternator 2 is increased), the rotation of the rotating capacitor 7 increases. , that is,
The output frequency increases and the output voltage of converter 4 decreases (if converter 4 has a diode configuration, AC generator 2
), the output frequency will decrease.

Therefore, by controlling the converter 4 (or by controlling the alternating current generator 2 if the converter 4 has a diode configuration), the output frequency can be controlled to be constant.

However, the 10 rotation range of the propeller motor is quite wide,
Therefore, although the output frequency of the alternating current generator 2 varies considerably, it is better as a shaft-driven power generator if it can be used over as wide a rotation range as possible of the prime mover 1.

When converting the output of the alternating current generator 2 to direct current using the converter 4, for example, if the converter 4 is considered as a three-phase bridge circuit, the semiconductor elements of each arm are sequentially switched in accordance with the phase order of the voltage. It has to flow.

The overlap angle of commutation at this time increases as the commutation reactance of the generator increases, and the conversion efficiency decreases.

However, the commutation reactance of AC generator 2 is
As the frequency increases, the conversion efficiency increases and decreases.

That is, if the rotational speed of the prime mover 1 increases, the output voltage of the converter 4 decreases even though the voltage of the alternator 2 is constant.

Experience has shown that when the rotational speed of the prime mover 1 doubles, the output voltage of the converter 4 decreases by about 10 to 20%.

The present invention has been made in view of these drawbacks, and will be explained in detail with reference to FIG. 2 showing an embodiment of the present invention. In the figure, devices with the same numbers as in FIG. 1 indicate the same devices.

Reference numeral 10 denotes a signal voltage circuit that generates a signal according to the rotational speed of the alternator 2, and its output is used to configure a compensation circuit that compensates for a decrease in conversion efficiency of the converter 4.

The operation will be explained below. By generating a signal proportional to the rotational speed of the alternator 2 by the signal voltage circuit 10 and adding this to the AVR 3, the output voltage of the alternator 2 is changed to the rotational speed of the prime mover 1. If it increases, the rotation speed N in Figure 3
As shown in the characteristic diagram of the output voltage V of the alternating current generator 2, the output voltage V is increased from A to B to compensate for the decrease in efficiency of the converter 4, which is a conversion circuit.

In addition, although the rotation speed was taken up as the input of the signal voltage circuit 100,
Even if this is input using the frequency of the alternator 2, the same effect will be obtained.

Furthermore, the same effect can be obtained even if the circuit after the converter 4 is provided with a DC motor directly connected to an AC generator.

[Brief explanation of drawings]

Figure 1 is a circuit diagram of a conventional shaft-driven power generator, Figure 2 is a circuit diagram of a shaft-driven power generator having a compensation circuit according to the present invention, and Figure 3 shows the relationship between the rotational speed and output voltage of the alternator. It is a characteristic diagram. 1... Prime mover, 2... AC generator, 3
...AVR, 4...Converter, 5.
...Reactor, 6...Inverter, 7
...Rotating capacitor, 8...AVR,
10...Signal voltage circuit.

Claims (1)

[Claims] 1. An alternating current generator driven by a prime mover whose rotation speed changes, a semiconductor converter that rectifies the voltage of this alternator, a separately excited inverter that converts the DC voltage of this semiconductor converter into alternating current, and a current flowing to this separately excited inverter. In a power generation device configured with a rotating capacitor that supplies , a compensation circuit for a shaft drive generator configured to apply an output of the signal voltage circuit to an automatic voltage regulation circuit of the alternator.