JPH048184A - Driving method of induction motor - Google Patents

Abstract

PURPOSE:To share a current control system among a plurality of inverters by employing multiplex input windings in an induction motor and feeding power to each winding from individual inverter thereby obviating the necessity of quadrature current suppression. CONSTITUTION:Input windings 31, 32 of an induction motor 30 comprises coil groups wound around respective pole coils 41-44 or respective sets of a plurality of pole coils 41-44 while being insulated one another, where voltages having same phase and same amplitude are fed from individual inverters 7A, 7B to respective pole coils 41-44 or respective sets of pole coils 41-44. Since multiplexed outputs from the plurality of inverters 7A, 7B are not fed to the input windings 31, 32, quadrature current is not required to be suppressed. Consequently, the plurality of inverters 7A, 7B do not require a current control loop for controlling DC component, i.e., the quadrature current, and the inverters 7A, 7B can be controlled through a common current control system.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application] The present invention relates to a method for driving an induction motor using a plurality of inverters.

[Conventional technology]

When driving a large-capacity induction motor using a power converter (inverter), there is a limit to the capacity of a single inverter, so a method is adopted in which inverters are operated in parallel as shown in FIG.

In FIG. 5, 1 is a first inverter device, 10 is a second inverter device, the output terminals of both inverter devices are connected via a DC reactor 20, and the inductor is AC power is supplied to the electric motor 30A. U phase, ■ phase, W of this induction motor 30A
The phase input winding is a single winding (illustrated in Figure 6). Each of the inverter devices 1 and 1O has a current control system independent from the other. 2 is an error amplifier that amplifies the deviation between the current command value and the current foothack value; 3 is a comparator that compares the output of the carrier wave generation circuit 4 and the error amplifier 2; 5 is a PWM control circuit; 6 is a driver; 7A; 7B indicates an inverter, and 8 indicates an impark power supply.

FIG. 6 shows one phase (U phase) of the input winding (four poles connected adjacent to each other) of a three-phase four-pole induction motor, and various coils are connected in parallel inside the motor. The illustrated N and S poles indicate various polarities when current flows in the direction of the illustrated arrow.

[Problem to be solved by the invention]

Conventionally, an induction motor whose input winding is a winding for a single power supply is driven by a plurality of inverter devices operated in parallel. , 7B, it is necessary to suppress the galvanic current caused by the switching time difference of the switching elements composing the switching elements. In order to suppress the galvanometric current as a DC component, both inverter devices 1.10 each have a current control loop.

As a result, the cost is high, and since there are two control systems, both controlling the input terminal of the induction motor 30 and controlling the cross current, there is a problem that the stability range is narrow.

This invention was made to solve the above problems.
There is no need to provide galvanometric countermeasures on the inverter side,
The configuration of the inverter example can be simplified, and when driving a large-capacity induction motor using multiple inverters,
It is an object of the present invention to provide a method for driving an induction motor that can significantly alleviate constraints caused by the capacity of a single inverter and the galvanized current.

[Means to solve the problem]

In order to achieve the above object, when an induction motor is driven using a plurality of inverters, in claim 1, each phase of the input winding of the induction motor is arranged for each pole coil or for a plurality of pole coils. It consists of a group of coils that are insulated and wound for each set, and each pole coil is configured to supply a voltage of the same phase and same amplitude from a separate inverter to each pole coil set, Claim 2 In this case, the input winding of the above-mentioned induction motor is a multiple winding type having a plurality of mutually insulated windings, each winding is supplied with power from a separate inverter, and these inverters are controlled by a common current control system. According to a third aspect of the present invention, the control system has an interloop configuration.

[Operation] In the present invention, power is supplied to each pole coil or each pole coil set of each phase of the input winding of an induction motor from a separate inverter,
Alternatively, each winding of the multi-winding type input winding is supplied with power from a separate inverter, and the outputs of a plurality of inverters are not multiplexed and provided, so the above-mentioned cross current problem does not occur.

[Example] Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

In FIG. 1, 30 is a three-phase induction motor, and its input windings are connected to two sets of mutually insulated three-phase human-powered motors 31.
The first input winding 31 is supplied with three-phase AC power from the inverter 7A, and the second input winding 31! Here, three-phase AC power is supplied from the inverter 7B, 69 is a current detector DCCT, and both inverters 7A and 7B are output-controlled by a common current control system.

In this embodiment, the first input winding 31 of the induction motor 30 receives three-phase AC from the inverter 7A to generate a rotating magnetic field, and the second human-powered winding 32 receives three-phase AC from the inverter 7B. The outputs of both inverters 7A and 7B are multiplexed to generate a rotating magnetic field, and the input windings 31 and 32 are
Therefore, the above-mentioned galvanic current problem does not occur. Therefore, it is not necessary to provide a current control loop for controlling the galvanometric current as a DC component in both inverters 7A and 7B, and the inverters 7A and 7B can be controlled by a common current control system.

FIG. 2 shows an example of an open loop control system, and for the same reason, the current control system of inverters 7A, 7B and 7C can be made common. This induction motor 30
has three sets of mutually independent windings 31, 32, 33.

In addition, in the above embodiment, the manual winding of the induction motor 30 is
However, if multiple windings of 4Mi or more are used, power can be supplied from four or more inverters, so the power supply capacity can be easily increased.

In each of the above embodiments, the input winding of the induction motor 30 is a multiple winding, but each phase of the input winding is insulated and separated every two pole coils as shown in FIG. By supplying power to each pole coil set from a separate inverter, the galvanic current problem can be solved.

Figure 3 shows the phase input windings of a three-phase, four-pole induction motor. It is insulated and separated from the set of the pole coil 43 and the fourth pole coil 44, and power is supplied between the terminals Ul and Xi from the first inverter, and between the terminals U2 and X2 from the second inverter. In this case, the output phases of both inverters are the same and the voltages have the same amplitude.

Of course, as shown in FIG. 4, each pole coil 41 to 44 may be insulated and separated, and voltages of the same phase and amplitude may be supplied to each of them from a separate inverter.

C Effects of the Invention] As explained above, the present invention uses the manual winding of the induction motor as a multiple winding, and supplies power to each winding from a separate inverter, and also connects each phase of the input winding to each pole coil or By insulating and separating each multi-pole coil and supplying power to each from a separate inverter, the problem of cross current current is eliminated, making it possible to share the current control system for multiple inverters and suppressing cross current. Since there is no need to provide a function for can be significantly alleviated.

[Brief explanation of drawings]

FIG. 1 and FIG. 2 each show an embodiment of the present invention;
Figures 3 and 4 are wiring diagrams of induction motor input windings showing other embodiments of the present invention, Figure 5 is a block diagram for explaining a conventional induction motor driving method, and Figure 6 is a block diagram for explaining a conventional induction motor driving method. The figure is a wiring diagram showing an example of a conventional manual winding for an induction motor. 7A, 7B-inverter,

Claims (3)

[Claims] (1) When driving one induction motor using multiple inverters, each phase of the input winding of the induction motor is insulated and wound for each pole coil or for each set of multiple pole coils. It consists of a group of coils that are rotated, and each pole coil or each pole coil set is connected to the same phase and
A method for driving an induction motor characterized by supplying voltages of the same amplitude. (2) In the case of driving an induction motor using multiple inverters, the input winding of the induction motor is a multiple winding type having multiple windings insulated from each other, and each winding is connected to a separate inverter. A method for driving an induction motor, characterized in that the inverters are controlled by a common current control system. (3) The method for driving an induction motor according to claim 2, wherein the control system is an open loop.