CS201630B1 - Connection of recuperation circuit of the current alternator with the forced commutation - Google Patents

Description

The invention relates to the connection of a recuperative circuit of a current inverter with forced commutation, which reduces the losses in the commutating circuits and guarantees reliable operation of the inverter even at higher frequencies.

The commutating circuits of the current inverters with forced commutation used up to now have relatively large capacitances of the commutating capacitors, which, among other things, create difficulties in operating at higher frequencies, with a greater range of inverter current changes and higher load inductances. Connections are known which improve the operation of the commutating circuits by moving most of the commutating capacitors into an accumulation circuit connected to the inverter output and the stored energy being pumped by the discharge resistor or recovered by the inverter-led network through the isolation transformer to the ground. Resistance discharging is uneconomical, power inverter recovery is complicated and increases equipment failure rate. The requirements for smaller and cheaper commutation circuits are also solved in such a way that the electric motors intended for feeding from the inverters are designed with reduced stray inductances. Motors designed in this way are not suitable for direct connection to the mains.

The above-mentioned drawbacks are substantially eliminated by the solution according to the invention, which consists in that an accumulator circuit consisting of a rectifier and a capacitor is connected in series between its power source and the inverter by its output terminals.

201 JJO input is the isolator transformer connected output of the inverter. The terminals are alternatively »connected to the output of the auxiliary voltage source, parallel to the storage circuit, and alternatively an electronic switch is connected.

The circuitry according to the invention allows reliable operation of the inverter with a greater range of inverter operating current and higher inductances and loads, such as series-produced asynchronous motors. The connection does not increase the demands on the inverter's control circuits. The accumulator circuit capacitors may be of the electrolytic type, reducing their cost and capriciousness.

The invention is illustrated in the accompanying drawings, in which: FIG. 1 shows the recovery circuit connection and FIG. 2 another example of wiring. The wiring in FIG. 1 comprises a current source 2 ' a controlled pulse and smoothing choke or an uncontrolled β pulse converter and smoothing choke, a forced commutate inverter 2 »load 2» consisting generally of induction motors, an isolation transformer 2 »an accumulator circuit 2, and an auxiliary voltage source 6. FIG. 2, an electronic switch 6 is connected in series in parallel to the converter circuit.

In the circuit according to FIG. 1, the current source 2 maintains the required current in the converter circuit by the load 6. Overvoltage arises at the output voltage of the inverter 2 due to the load inductance 6 and the operation of the commutating circuits of the inverter 2. The output voltage, together with the reclamer, is fed via a separate transformer 2 ^{to an} accumulator circuit 2 formed by a buffer and a capacitor. The size of the overvoltage is thus limited by the voltage level of the capacitors in the accumulation circuit. The discharging of the capacitors of the storage circuit is initiated by the serial connection with the converter current circuit through terminals A, B.

The minimum voltage value of the capacitors of the storage circuit 2 can be ensured by simultaneously connecting the auxiliary voltage source 6 to the terminals A, Β. In the circuit according to FIG. 2, the voltage of the capacitors of the accumulation circuit 2 is maintained at least by an electronic switch 2 »connected in series parallel to the accumulation circuit 2,

A further advantage of the invention is that it reduces the need to modify the commutating circuits of the inverter when changing the size and type of load. This allows the aa to be used more easily in the field of drives and aynchronous motors.

Claims (3)

CLAIMS 1. A recuperative circuit of a forced inverter current inverter, characterized in that an accumulator circuit (2), consisting of a buffer and a capacitor, is connected in series between its current source (1) and the inverter (3) by its output terminals (A, B). the inverter output (3) is connected to its input by an isolation transformer (5). 201 830 2. The connection according to claim 1, characterized in that the output terminals of the auxiliary voltage supply (6) are connected to the output terminals (A,>) of the storage circuit (2). 3. Connection according to claim 1, characterized in that an electronic switch (7) is connected in series parallel to the accumulation circuit (2).