On the Joint Operation of Two Shock Generators During Energy Accumulation in an Inductive Load

G. A. Sipailov, A. V. Loos

(Presented by the scientific seminar of the departments of Electrical Machines and General Electrical Engineering)

Existing circuits for accumulating energy from a shock generator in an inductive load over the course of many half-waves of an emf of one sign have a significant drawback, namely that the time of energy storage between two accumulation cycles is rather long. This leads to considerable energy losses in the active resistances of the “load—short-circuit” circuit [1, 2].

The time of energy storage between two accumulation cycles can be substantially reduced if energy transfer is carried out during each half-period of the emf. This can be done most simply by using a two-phase shock generator whose emf phases are shifted by 180 electrical degrees. It is also possible to use two single-phase shock generators having an analogous phase shift between the emfs.

Fig. 1. Schematic diagram of operation.

The schematic diagram of the operation of two single-phase generators on an inductive load is shown in Fig. 1, where UG-1, UG-2 are single-phase shock-power generators; K-1, K-2, K-3 are arc-free ion-mechanical switching devices; \(L_{\mathrm{n}}, r_{\mathrm{n}}, L_{\mathrm{g}}, r_{\mathrm{g}}\) are the parameters of the load and the generators.

The nature of the variation of the currents and emfs of the generators is shown in Fig. 2.

The circuit operates as follows. In the initial state K-1, K-2, K-3 are open. The generators operate at no load. At the time \(t=0\), by closing K-1 we connect generator UG-1 to the load.

The nature of the variation of the current \(i_{\mathrm{g}1}=i_{\mathrm{n}}\) is determined from the solution of equation (1):

\[ E_{\mathrm{m}}\sin \omega t = L_{\mathrm{g}}\frac{di_{\mathrm{g}1}}{dt} + r_{\mathrm{g}} i_{\mathrm{g}1} + L_{\mathrm{n}}\frac{di_{\mathrm{n}}}{dt} + r_{\mathrm{n}} i_{\mathrm{n}} . \tag{1} \]

At the time \(t_1\), when the load current reaches a maximum, we close K-2. The nature of the variation of the currents in this case is determined by the solution of equations (1), (2), and (3):

Fig. 2. Character of the variation of the currents
and emf.

\[ E_m \sin(\omega t-\pi)=L_r \frac{di_{r2}}{dt}+r_r i_{r2}+L_H \frac{di_H}{dt}+r_H i_H, \tag{2} \]

\[ i_H=i_{r1}+i_{r2}. \tag{3} \]

From this instant of time a rapid increase of the current \(i_{r2}\) begins, and the current \(i_{r1}\) decreases. At the instant when the current \(i_{r1}\) passes through zero, switch K-1 is opened. The load current in the time interval from \(t_1\) to \(t_2\) remains practically constant. From the instant \(t_2\), the transient process in the circuit is described by equation (2). The load current again increases, and at the instant when it reaches its maximum, \(t_3\), switch K-1 is closed. The generator current \(i_{r2}\) rapidly decreases, and at the instant when it passes through zero generator UG-2 is disconnected by opening K-2. At the same time the current of generator UG-1 increases sharply. In the time interval from \(t_3\) to \(t_4\), the current in the load is maintained constant, and then increases again. Thereafter the processes in the circuit repeat. The maximum value of the current that can be obtained in the load is equal to the surge short-circuit current of the generator.

In order to clarify the capabilities of the circuit under consideration and to compare it with the energy-storage circuit using a single shock generator, studies of it were carried out according to equations (1), (2), (3). The studies of the operation of the circuit were performed on an MNB-1 analog machine with the use of a programming device that ensured automatic variation of the structural scheme of the solution in accordance with the changes in the circuit being investigated. The mathematical model of the circuit under consideration is shown in Fig. 3.

In investigating the circuit, the value of the ratio

\[ \frac{L_H}{L_r} \]

was varied within the limits \(1 \div 10\). The ratios between the active and inductive co-

Fig. 3. Mathematical model of the circuit.

resistances were chosen equal to \(\dfrac{r_{\mathrm{g}}}{x_{\mathrm{g}}}=\dfrac{r_{\mathrm{n}}}{x_{\mathrm{n}}}=0.05\). The results of these studies are presented in Table 1.

Table 1

As can be seen from the table presented, the time required to reach a current equal to \(0.9 I_{\mathrm{ud}}\), when the circuit under consideration is operating, is more than two times less than when energy is accumulated in an inductive load from a single shock generator. The dissipation of active energy in the resistances of the circuit in this case will also be approximately two times smaller.

Thus, when operating according to this circuit, the power of the entire installation increases by more than a factor of two. Figure 4 shows an oscillogram of the solution for \(L_{\mathrm{n}}/L_{\mathrm{g}}=2.5\).

The use of this circuit may prove expedient in those cases when a significant increase in the rate of energy transfer to an inductive load is necessary.

Fig. 4. Oscillogram of the solution on an analog computer.

REFERENCES

1. V. V. Ivashin, A. V. Loos, G. A. Sipailov, K. A. Khorkov. A circuit for increasing the energy and the rate of its transfer from a shock generator to an inductive load, Izvestiya TPI, vol. 139, 1965.

2. V. V. Ivashin, A. V. Loos, G. A. Sipailov. Accumulation of energy in an inductive load from a shock generator, Izvestiya TPI, vol. 145, 1966.