US 4,302,713 A · Fixed gating sequence apparatus and method for an inverter

Abstract

A fixed gating sequence apparatus and method for an inverter is disclosed. In one aspect of the invention, an outgoing signal of variable frequency is generated by the inverter in response to gating signals provided by an inverter control. The gating signals effectively are provided by a shift register of an inverter control to the gates of the conduction controlled rectifying devices in the inverter in response to a clocking signal. The clocking signal is provided to the clock input of the shift register at a normal system rate when an idle condition (idle control signal) is not present and at a predetermined cycling rate from when the idle condition occurs until a desired fixed gating pattern effectively is provided by the shift register to the inverter. The shift register remains at the stage providing the desired fixed gating pattern until the idle condition no longer is present, whereupon the normal clocking signals are again provided to the shift register. In another aspect, the gating signals, which effectively are normally supplied to the conduction controlled rectifying devices of the inverter, are blocked or inhibited from when the idle condition occurs until the desired fixed gating pattern is provided by the shift register of the control stage of the inverter. Thus, in this aspect, the inverter does not produce a moderate frequency burst of outgoing signal when the shift register cycles through and stops at the desired fixed gating pattern.

Claims15

Dependent claims

In an inverter system of the type that provides gating signals in a prescribed sequence in response to a selectively applied clocking signal to thereby control the application of electrical power to an associated electric motor, the improvement comprising:

(a) means for supplying an externally generated idle control signal when a zero speed, zero torque mode of motor operation is desired;
(b) means for providing gating signals in response to a clocking signal;
(c) generating means for generating said clocking signal at a controllable rate in response to an externally supplied controllable voltage signal;
and at a predetermined rate in response to an externally supplied voltage signal of a predetermined magnitude;
(d) means for providing said gating signals to said system in response to a one of said gating signals and said idle control signal including,
(1) first logic means for providing a first control signal except in response to said one of said gating signals and said idle control signal, and
(2) second logic means for providing said clocking signal to said inverter system except in the absence of said first control signal;
and,
(e) third logic means for providing said voltage signal of a predetermined magnitude to said generating means in response to said idle control signal and in the absence of said one of said gating signals.

6 more elements

An electric motor apparatus having an AC electric motor producing a rotation in response to a drive current of variable magnitude and frequency comprising:

(a) means for establishing a rotation reference signal proportional to a desired level of rotation;
(b) means for generating an actual rotation signal proportional to said rotation;
(c) means for generating a rotation difference signal representative of any difference between said rotation reference signal and said actual rotation signal;
(d) means for producing a torque command signal in accordance with said rotation difference signal, and for producing a frequency control signal and a current control signal as functions of said torque command signal;
(e) means for generating a clocking signal in response to said frequency control signal;
(f) means for providing gating signals in response to said clocking signal;
(g) means for generating an idle control signal when said torque command signal and at least two of said actual rotation signal, said rotation reference signal and said rotation difference signal are less than respective predetermined levels;
(h) means for supplying to said motor said drive current at a magnitude varied in accordance with said current control signal and at a frequency controlled in response to said gating signals;
and
(i) means connected to said means for providing gating signals for providing said clocking signal except in response to one of said gating signals and said idle control signal.

7 more elements

An electric motor method having an AC electric motor producing a rotation in response to a drive current of variable magnitude and frequency comprising the steps of:

(a) establishing a rotation reference signal proportional to a desired level of rotation;
(b) generating an actual rotation signal proportional to said rotation;
(c) generating a rotation difference signal representative of any difference between said rotation reference signal and said actual rotation signal;
(d) producing a torque command signal in accordance with said rotation difference signal;
(e) producing a frequency control signal and a current control signal as functions of said torque command signal;
(f) generating a clocking signal in response to said frequency control signal;
(g) providing gating signals in response to said clocking signal;
(h) generating an idle control signal when said torque command signal and at least two of said actual rotation signal, said rotation reference signal and said rotation difference signal are less than respective predetermined levels;
(i) supplying to said motor said drive current at a magnitude varied in accordance with said current control signal and at a frequency controlled in response to said gating signals;
and,
(j) providing said clocking signal except in response to one of said gating signals and said idle control signal.

8 more elements

Dependencies are inferred from the claim text.

Fixed gating sequence apparatus and method for an inverter

Life of this patent

Fixed gating sequence apparatus and method for an inverter

Life of this patent

Abstract

Claims15