Pole change induction motor and control apparatus and method for the same

A method for speed controlling a pole change induction motor, comprising the steps of:

• (a) providing a pole change induction motor capable of changing its number of poles between an n number of poles and a 2n number of poles, wherein n is equal to one of 2 and 4, and having stator windings, the stator windings including six lead terminals;
• (b) providing inverter means for frequency controlled three-phase powers for two groups of said stator windings, each of the two groups comprising one of two groups of lead terminals, each of said groups of lead terminals having three lead terminals;
• (c) measuring a rotation speed of the pole change induction motor;
• and
• (d) receiving the measured rotation speed (.omega.r) of said pole change induction motor and a speed instruction (.omega.r*), and controlling output phases derived from said inverter means to the stator windings via each of the two groups of lead terminals to provide one of
• (i) same phases for the outputs of said inverter means;
• and
• (ii) phases of the outputs of said inverter means such that each phase of the outputs at respective phases of said inverter means is shifted sequentially by 2 .pi./3 for the two groups of lead terminals when said induction motor is driven in a constant power operation range and the rotation speed of the motor falls in a low speed range below a predetermined rotation speed, whereby the induction motor is driven with the number of poles being changed to the 2n number of poles.

An apparatus comprising:

• a pole change induction motor constructed such that the number of poles of the motor can be switched between a first number of poles (n) and a second number of poles (2n), wherein n is equal to one of 2 and 4, the motor having stator windings arranged into two groups, each of the two groups having three lead terminals;
• at least one inverter for providing three-phase power for the two groups of lead terminals;
• measuring means for measuring a rotation speed (.omega.r) of the motor;
• and
• a controller for receiving the measured rotation speed (.omega.r) of the motor and a speed instruction (.omega.r*);
• wherein when the motor is driven in a constant output range and the rotation speed (.omega.r) of the motor falls in a low speed range below a predetermined rotation speed (af), and the number of poles of the motor is equal to the second (2n) number of poles, the controller controls the three-phase power provided by the at least one inverter via each of the two groups of lead terminals to provide one of
• (1) equivalent phases for the output of the at least one inverter, and
• (2) phases for the output of the at least one inverter such that each phase of the output at respective phases of the at least one inverter is sequentially shifted by 2 .pi./3 for the two groups of lead terminals;
• and
• wherein when the motor is driven in the constant output range and the rotation speed (.omega.r) of the motor falls in a high speed range exceeding the predetermined speed (af), and the number of poles of the motor is equal to the first (n) number of poles, the controller controls the three-phase power provided by the at least one inverter via each of the two groups of lead terminals to provide one of
• (1) 180.degree.-inverted phases for the output of the at least one inverter with an output frequency of each of the at least one inverters being halved, and
• (2) phases for the output of the at least one inverter such that each phase of the output at respective phases of the at least one inverter is sequentially shifted by .pi./3 for the two groups of lead terminals with an output frequency of each of the at least one inverters being halved.

An apparatus comprising:

• (a) a pole change induction motor adapted to change its number of poles between an n number of poles and a 2n number of poles, wherein n is equal to one of 2 and 4, and having stator windings, the stator windings including six lead terminals;
• (b) inverter means for providing frequency controlled three-phase powers for two groups of said stator windings, each of the two groups comprising three lead terminals;
• (c) measuring means for measuring a rotation speed of the pole change induction motor;
• and
• (d) controlling means for receiving the measured rotation speed (.omega.r) of said pole change induction motor and a speed instruction (.omega.r*), and controlling output phases derived from said inverter means to the stator windings via each of the two groups of lead terminals to provide one of
• (i) 180.degree.-inverted output phases for the outputs of said inverter means which are supplied to one of the two groups of lead terminals with the same phases provided for the outputs of said inverter means which are supplied to the other of the two groups of lead terminals, and provide output frequencies of the outputs of said inverter means to the two groups of lead terminals which are approximately half the output frequencies in a case when said induction motor is driven in the constant output range and the rotation speed of the motor falls in the low speed range below the predetermined rotation speed;
• and
• (ii) the phases of the outputs of said inverter means such that each phase of the outputs at respective phases of said inverter means is sequentially shifted by .pi./3 for the two groups of lead terminals and to provide the frequencies of the outputs at the respective phases of said inverter means for the two groups of lead terminals such that the output frequencies are approximately half the output frequencies when the induction motor is driven in the constant output driving and the rotation speed of said induction motor falls in the low speed range when the induction motor is driven in the constant output range and the rotation speed of said induction motor falls in a high speed range exceeding the predetermined speed, whereby the induction motor is driven with the number of poles being changed to the n number of poles.

A method for speed controlling a pole change induction motor, comprising the steps of:

• (a) providing a pole change induction motor capable of changing its number of poles between an n number of poles and a 2n number of poles, wherein n is equal to one of 2 and 4, and having stator windings, the stator windings including six lead terminals;
• (b) providing inverter means for frequency controlled three-phase powers for two groups of said stator windings, each of the two groups comprising three lead terminals;
• (c) measuring a rotation speed of the pole change induction motor;
• and
• (d) receiving the measured rotation speed (.omega.r) of said pole change induction motor and a speed instruction (.omega.r*), and controlling output phases derived from said inverter means to the stator windings via each of the two groups of lead terminals to provide one of
• (i) 180.degree.-inverted output phases for the outputs of said inverter means which are supplied to one of the two groups of lead terminals with the same phases provided for the outputs of said inverter means which are supplied to the other of the two groups of lead terminals, and provide output frequencies of the outputs of said inverter means to the two groups of lead terminals which are approximately half the output frequencies in a case when the induction motor is driven in the constant output range and the rotation speed of the induction motor falls in the low speed range below the predetermined speed;
• and
• (ii) the phases of the outputs of said inverter means such that each phase of the outputs at respective phases of said inverter means is sequentially shifted by .pi./3 for the two groups of lead terminals and to provide the frequencies of the outputs at the respective phases of said inverter means for the two groups of lead terminals such that the output frequencies are approximately half the output frequencies when the induction motor is driven in the constant output driving and the rotation speed of said induction motor falls in the low speed range, when the number of poles being changed to the n number of poles.

An apparatus comprising:

• (a) a pole change induction motor adapted to change its number of poles between an n number of poles and a 2n number of poles, wherein n denotes an arbitrary number equal to 2 or more, and having stator windings, the stator windings including six lead terminals;
• (b) a single six-phase inverter which supplies frequency controlled six-phase currents to said lead terminals;
• (c) measuring means for measuring a rotation speed of the pole change induction motor;
• and
• (d) controlling means for receiving the measured rotation speed (.omega.r) of said pole change induction motor and a speed instruction (.omega.r*) and for controlling said six-phase inverter to provide either one of phases of the outputs of said six-phase inverter such that each phase of the outputs at respective phases of said six-phase inverter is shifted sequentially by 2 .pi./3 for two groups of the lead terminals of said stator windings when said induction motor is driven in a constant power operation range and the rotation speed of said induction motor falls in a relatively low speed range or the phases of the outputs of said six-phase inverter such that each phase of the outputs at respective phases of said six-phase inverter is sequentially shifted by .pi./3 for the two groups of the lead terminals of said stator windings when said induction motor is driven in the constant power operation range and the rotation speed of said induction motor falls in the relatively low speed range, and controlling the said six-phase inverter to provide frequencies of the outputs at the respective phases of said six-phase inverter for the two groups of the lead terminals of said stator windings when said induction motor is driven in the constant power operation range and the rotation speed of said induction motor falls in a relatively high speed range such that the output frequencies are approximately half those outputted when said induction motor is driven in the constant power operation range and the rotation speed of said induction motor falls in the relatively low speed range.

A method for speed controlling a pole change induction motor, comprising the steps of:

• (a) providing a pole change induction motor capable of changing its number of poles between an n number of poles and a 2n number of poles, wherein n is equal to one of 2 and 4, and having stator windings, the stator windings including six lead terminals;
• (b) providing inverter means for frequency controlled three-phase powers for two groups of said stator windings, each of the two groups comprising three lead terminals;
• (c) measuring a rotation speed of the pole change induction motor;
• and
• (d) receiving the measured rotation speed (.omega.r) of said pole change induction motor and a speed instruction (.omega.r*), and controlling output phases derived from said inverter means to the stator windings via each of the two groups of lead terminals to provide one of
• (i) 180.degree.-inverted output phases for the outputs of said inverter means which are supplied to one of the two groups of lead terminals with the same phases provided for the outputs of said inverter means which are supplied to the other of the two groups of lead terminals, and provide output frequencies of the outputs of said inverter means to the two groups of lead terminals which are approximately half the output frequencies in a case when the induction motor is driven in the constant power operation range and the rotation speed of the induction motor falls in the low speed range below the predetermined speed;
• and
• (ii) the phases of the outputs of said inverter means such that each phase of the outputs at respective phases of said inverter means is sequentially shifted by .pi./3 for the two groups of lead terminals and to provide the frequencies of the outputs at the respective phases of said inverter means for the two groups of lead terminals such that the output frequencies are approximately half the output frequencies when the induction motor is driven in the constant power operation range and the rotation speed of said induction motor falls in the low speed range, when the number of poles being changed to the n number of poles.

An apparatus comprising:

• (a) a pole change induction motor adapted to change its number of poles between an n number of poles and a 2n number of poles, wherein n denotes an arbitrary number equal to 2 or more, and having stator windings, the stator windings including six lead terminals;
• (b) a single six-phase inverter which supplies frequency controlled six-phase currents to said lead terminals;
• (c) measuring means for measuring a rotation speed of the pole change induction motor;
• and
• (d) controlling means for receiving the measured rotation speed (.omega.r) of said pole change induction motor and a speed instruction (.omega.r*) and for controlling said six-phase inverter to provide either one of phases of the outputs of said six-phase inverter such that each phase of the outputs at respective phases of said six-phase inverter is shifted sequentially by 2 .pi./3 for two groups of the lead terminals of said stator windings when said induction motor is driven in a constant power operation range and the rotation speed of said induction motor falls in a relatively low speed range or the phases of the outputs of said six-phase inverter such that each phase of the outputs at respective phases of said six-phase inverter is sequentially shifted by .pi./3 for the two groups of the lead terminals of said stator windings when said induction motor is driven in the constant power operation range and the rotation speed of said induction motor falls in the relatively low speed range, and controlling the said six-phase inverter to provide frequencies of the outputs at the respective phases of said six-phase inverter for the two groups of the lead terminals of said stator windings when said induction motor is driven in the constant power operation range and the rotation speed of said induction motor falls in a relatively high speed range such that the output frequencies are approximately half those outputted when said induction motor is driven in the constant power operation range and the rotation speed of said induction motor falls in the relatively low speed range.