Winding change-over switch of three-phase AC motor

Abstract

A winding change-over switch of a three-phase AC motor which can switch the motor current quickly while minimizing disturbance of a sine wave current and can prevent an abnormal operation or the destruction of an apparatus by detecting wrong wiring or abnormality of a component. A winding change-over section ((2(11)) connects a positive-side charging resistor (5(14)), a negative-side charging resistor (21(22)) and a capacitor (6(15)) in series between the DC positive-side bus (9) and the DC negative-side bus (10) of an inverter (7), connects the positive side of the capacitor with the cathode of a diode portion (3(12)) and then changes over a high-speed winding to from a low-speed winding under such a state that the potential of the capacitor is equalized to the DC bus voltage of the inverter. In addition, wrong wiring or abnormality of a component is detected by means of a state detector (25(27)) and a comparator (26(28)).

Description

technical field [0001] The invention relates to a winding switching device of a three-phase AC motor that expands the speed control range by switching the windings of the three-phase AC motor, and is aimed at the industrial fields including vehicle drive, machine tool spindle drive and servo devices. Background technique [0002] In inverter-driven machine tool spindles and vehicle drive devices, a winding switching method is adopted as a means of obtaining a sufficiently large torque in a low-speed range while realizing operation in a high-speed range (for example, refer to Patent Document 1) . [0003] Figure 5 It is a diagram showing an example of a conventional winding switching device for a three-phase AC motor. according to Figure 5 , the existing winding switching device will be described. [0004] For the three-phase AC motor 111, outside the motor, there are center taps (TU2, TV2, TW2) of each phase winding, winding start terminals and winding end terminals of e...

AI Technical Summary

Problems solved by technology

Therefore, the sinusoidal current flowing in the full-wave rectifier 113 and the semiconductor switch 114 is disturbed.

Moreover, a current flows through the resistor 125 constituting the snubber circuit, causing the sine wave current to be disturbed

[0009] In this way, there is the following problem: when the motor winding changes from the excitation state to the non-excitation state, the energy accumulated in the inductance of the motor winding is released, so the current switching cannot be performed instantaneously, and the motor current that should be a sine wave is disturbed.

However, when assembling components, if the high-speed side control signal is wired to the low-speed side and the low-speed side control signal is wired to the high-speed side by mistake (such a wrong wiring usually does not occur), it will run in the low-speed area. At this time, the current required to obtain the desired torque will increase significantly, which will cause abnormal operation such as overcurrent

Moreover, during high-speed operation, the induced voltage of each phase of the motor rises abnormally, causing overvoltage and damage to the power semiconductor switching elements of the inverter driving the motor and the winding switching device.

In addition, when the power semiconductor switching element of the winding switching part fails, it will cause abnormal operation such as single-phase operation or overcurrent operation.

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