2 speed 2/4-pole PSC/PSC motor with independent main windings and shared auxiliary winding

A PSC/PSC motor for 2-pole operation and 4-pole operation. The motor uses an independent 2-pole main winding and an independent 4-pole main winding. An auxiliary winding includes an independent 2-pole auxiliary winding, an independent 4-pole auxiliary winding, and a shared auxiliary winding used in both the 2-pole operation and the 4-pole operation.

FIELD OF THE INVENTION

The present invention generally relates to a two speed motor. In particular, the invention relates to a 2-speed permanent split capacitor (PSC) motor having independent main and auxiliary windings and both a shared auxiliary winding and a run capacitor.

BACKGROUND

For spa and swimming pool pumps, two different speeds are needed. When such pumps are driven by a 2/4-pole motor, a 2-pole speed is needed to run the full-load operation, i.e. create a water whirlpool, and a 4-pole speed is needed to run a light load, i.e., circulate the water. Because of the nature of the pump loads, the 4-pole output power is about ⅛ of the output power of the 2-pole operation. A PSC motor has been used for the 2-pole operation and a split phase or capacitive-start motor has been used for both 4-pole start and 2-pole start operations. The 4-pole operation uses the main winding only. Thus, the 4-pole efficiency is low. For example, a 2.5 Hp may have a 77% efficiency for 2-pole operation and a 48% for 4-pole operation.

In other similar products, a PSC motor has been used for 2-pole running and a capacitive-start motor has been used for both 4-pole start and 2-pole start. Again, the 4-pole run uses the main winding only.

In yet other similar products, a PSC/PSC motor solution has been used with independent main and auxiliary windings for the 2-pole PSC running. It also uses independent main and auxiliary windings for 4-pole PSC running. This solution has shortcomings and limitations. When the 2-pole winding is in operation, the 4-pole winding is idle. When the 4-pole winding is in use, the 2-pole winding is idle. Thus, the motor's windings are not efficiently used.

In U.S. Pat. No. 5,825,111, for “Single Phase Induction Motor 4/6 Pole Common Winding Connection with Magnetic Motive Force Symmetrically Distributed,” co-invented and co-assigned with this application, a winding connection for a 4/6-pole PSC/PSC motor for a washer application is described. In this connection approach, a portion of the 4-pole main winding and a portion of 4-pole auxiliary winding become the 6-pole main winding and another portion of the 4-pole winding and another portion of the 4-pole auxiliary winding become the 6-pole auxiliary winding. It requires 11 leads and 7 single-pole double-through switches for switching between pole configurations.

U.S. Pat. No. 6,707,214, for “PSC Motor Having a 4/6 Pole Common Winding and Having an Additional 4-Pole Winding,” co-invented and co-assigned with this application, is an improvement for U.S. Pat. No. 5,825,111. With an additional 4-pole winding, the performance for both speeds improves without increasing the lead and switch numbers.

In U.S. Pat. No. 6,175,209, for “2/4-pole PSC Motor with Shared Main Winding and Shared Auxiliary Winding,” co-invented and co-assigned with this application, a winding connection for a 2/4-pole PSC/PSC motor for compressor application is described. In this connection approach, a 2-pole main winding becomes a 4-pole main winding and a 2-pole auxiliary winding becomes a 4-pole auxiliary winding through reconnection. The 2/4-pole main winding and the auxiliary winding are not 90 degree apart in space. The electrical angle between the 2-pole main and auxiliary windings is lower than 90 degree. The electrical angle between the 4-pole main winding and auxiliary winding is higher than 90 degree. The deviation from 90 degree for both represents a compromise in performance for both speeds. This approach requires 4 single-pole double throw switches for switching between pole configurations.

With the recent desire to increase energy conservation, there is a need to raise the 4-pole efficiency of water recreational pump motors. Also, many capacitive-start motors require a centrifugal actuator with the starting switches. A motor design which features a centrifugal starting switch is statistically less reliable than designs without it. Thus, there is also a need to develop such a motor which does not require a centrifugal starting switch and which does not require additional switches for switching between pole configurations.

SUMMARY

To solve the above efficiency problems as well as other problems, the invention comprises a PSC/PSC motor for 2-pole operation and 4-pole operation. The motor uses separate windings for 2-pole main and auxiliary windings and 4-pole main and auxiliary windings. The motor shares windings between the 2-pole auxiliary winding and 4-pole auxiliary winding.

The reconnection (and circulating current isolation) between the 2-pole and 4-pole operations is realized by a relay with one single-pole double throw switch. No additional switches internal to the motor are needed for switching between pole configurations, other than the relay; an external switch is used for selecting 2-pole operation or 4-pole operation. Because the 2-pole auxiliary winding uses thicker wire, the magnetic wire loss in the 4-pole auxiliary winding is reduced. As a result, the active material cost is reduced and the motor efficiency is improved.

DESCRIPTION

FIG. 1is a schematic diagram of the electrical circuit of one embodiment of the motor according to the invention illustrating the independent main windings, the partially shared auxiliary windings and their inter-connection. As shown inFIG. 1, the present invention is a motor100having a 2-pole main winding102and a 4-pole main winding104which are independent of each other. A 4-pole auxiliary winding106includes a common portion or shared winding108A of a 2-pole auxiliary winding108A,108B. The 2-pole main winding102and the 2-pole auxiliary winding108B may be in series with an optional 2-pole protector110to filter surges in voltage or current during 2-pole operation. Similarly, the 4-pole main winding104and the 4-pole auxiliary winding106may be in series with an optional 4-pole protector112to filter surges in voltage or current during 4-pole operation. A relay114controls the motor configuration and, in particular, whether the motor100is configured for operating in a 2-pole mode or a 4-pole mode.

The embodiment ofFIGS. 1 and 2illustrates a 2 speed 2/4-pole PSC/PSC with independent main windings and shared auxiliary windings, having configurations in which a capacitor115is in series with the 2-pole auxiliary winding108A,108B and in which the capacitor115is in series the 4-pole auxiliary winding106,108A. However, it is contemplated that other configurations may be employed as embodiments of the invention.

In operation, selected input ports of a connector (see reference character202,FIG. 2) are powered by an external control circuit. Relay114is normally in a position in which contacts between terminals4and5of switch118are closed, as illustrated inFIG. 1.

For low speed operation, an input port L and a common input port COM of connector202are powered to energize the 4-pole main winding104, the 4-pole auxiliary winding106and the shared winding108A. A solenoid116of the relay114is not connected to the 4-pole main winding104and is not energized simultaneously with the 4-pole winding104. Thus, relay switch118remains in its normal position to close a circuit between contacts4and5, resulting in energizing the 4-pole auxiliary winding106and the shared winding108A.

For high speed operation, an input port H and a common input port COM of connector202are powered to energize the 2-pole main winding102, the 2-pole auxiliary winding108B and the shared winding108A. The solenoid116of the relay114, connected in parallel with the 2-pole main winding102, is energized simultaneously causing relay switch118to close a circuit between contacts2and4, resulting in energizing the 2-pole auxiliary winding108B and the shared portion108A of the 2-pole auxiliary winding108A,108B. Thus, relay switch118is energized to close a circuit between contacts4and2, resulting in energizing the 2-pole auxiliary winding108A,108B.

FIG. 2is a diagrammatic view of the wire connections of one embodiment of the motor100according to the invention.FIG. 2illustrates one embodiment of the positions of the windings and is color coded to match the color code illustrated inFIG. 1. As illustrated, the 2-pole main winding102may be positioned within the bottom of slots308of stator core304(seeFIG. 3), and the 4-pole main winding104may be positioned at the top of the slots308. The fact that the 4-pole main winding104is at the top of the slots308helps improve the 4-pole efficiency. The common portion108A of the 2-pole auxiliary winding that is shared may be located in the middle of the slots308.

According to one embodiment, both the 2-pole operating configuration of the motor100and the 4-pole operating configuration of the motor100need a certain minimum level of starting torque, e.g., around 10 oz-ft. Also, the 4-pole operating configuration needs about ⅛ of the output horsepower of the 2-pole operating configuration. As a result, the 4-pole main winding104can be wire of a smaller diameter and use less active magnetic material (e.g., copper or aluminum wire) than the wire used for the 4-pole auxiliary winding106. In addition, using the common portion108A of the 2-pole auxiliary winding as a shared portion of the 4-pole auxiliary winding saves more active material than sharing the 4-pole main winding from either 2-pole main winding or the 2-pole auxiliary winding. For example, the first auxiliary winding108B and the shared auxiliary winding108A comprise a copper wire having a larger diameter than the copper wire of the 4-pole main winding104and the second (4-pole) auxiliary winding106.

FIG. 3is a cross sectional plan view taken along a plane perpendicular to the axis of rotation of one embodiment of a rotor302and a stator core304of the motor100according to the invention. In this illustrated frame, the rotor302has 36 teeth306of substantially equal length and the stator core304has 24 slots308, 20 slots of substantially equal depth and 4 slots having a same, shorter depth.

Thus, in one embodiment viewed as having a shared auxiliary winding, the invention comprises a motor100having a stator core304and a rotor302in rotational relationship with the stator core304. A first main winding102has a 2-pole configuration and a second main winding104has a 4-pole configuration. In addition, auxiliary windings106,108include a shared auxiliary winding108A used in both the 2-pole configuration and the 4-pole configuration. An external switching circuit, including a connector202and related colored wires connecting the connector202to the windings102,104,106,108, selectively simultaneously energize the first main winding102and at least a common portion108A of the auxiliary winding in the 2-pole configuration and selectively simultaneously energizes the second main winding104and at least a common portion108A of the shared auxiliary winding in the 4-pole configuration.

In one embodiment viewed as having independent main windings with a partially shared auxiliary winding, the invention comprises a motor100having a stator core304and a rotor302in rotational relationship with the stator core304. A first independent main winding102has only a 2-pole configuration (e.g., energized only in a 2-pole configuration) and a second independent main winding104has only a 4-pole configuration (e.g., energized only in a 4-pole configuration). A partially shared auxiliary winding106,108A,108B has a first portion108A,108B which is energized in a 2-pole configuration and has a second portion106,108A, different than the first portion, which is energized in a 4-pole configuration. A switching circuit, including a connector202and related colored wires connecting the connector202to the windings102,104,108, selectively simultaneously energizes the first independent main winding102and the first portion of the first auxiliary winding108A,108B in the 2-pole configuration and selectively simultaneously energizes the second independent main winding104and the second portion of the second auxiliary winding106,108A in the 4-pole configuration.

In one embodiment viewed as having independent main windings with shared and independent auxiliary windings, the invention comprises a motor100having a stator core304and a rotor302in rotational relationship with the stator core304. A first independent main winding102has only a 2-pole configuration (e.g., energized only in a 2-pole configuration). A second independent main winding104has only a 4-pole configuration (e.g., energized only in a 4-pole configuration). A first independent auxiliary winding108B has only in a 2-pole configuration (e.g., energized only in a 2-pole configuration). A second independent auxiliary winding106has only in a 4-pole configuration (e.g., energized only in a 4-pole configuration). A shared auxiliary winding108A is energized in both a 2-pole configuration and a 4-pole configuration. A switching circuit, including a connector202and related colored wires connecting the connector202to the windings102,104,108, selectively simultaneously energizes the first independent winding102, the first auxiliary winding108B and the shared winding108A in the 2-pole configuration and selectively simultaneously energizing the second independent winding104, the auxiliary winding106and the shared winding108A in the 4-pole configuration.

In one embodiment, the relay configuration of the motor100is similar to a capacitive start 2/4-pole motors so that the same or similar components may be employed in both motors. For example, only a single capacitor115connected in series with the shared auxiliary winding106,108is used and the relay114of the switching circuit includes only one single pole, double throw switch118. As a result, the connections from an external control circuit to connector202correspond to the wiring connections to a capacitive start 2/4-pole motor.

Various embodiments of the invention achieve upwards to 80% efficiency for 2-pole operation and upwards to 60% efficiency for 4-pole operation. With design adjustments known to those skilled in the art and depending on frame size, teeth configuration, turns ratio, turns distribution, wire size, materials used, horsepower needed and other design parameters, embodiments of the invention may reach 81% efficiency for 2-pole operation and 62% for 4-pole operation. It is noted that, according to embodiments of the invention, the reconnection of the windings between the 2-pole and 4-pole operations is realized by a single relay114comprising one single-pole double-throw switch118.

In addition to directing power to the proper 2-pole or 4-pole circuit configuration, the relay114isolates and open circuits the circulating-currents in the auxiliary windings by applying normally closed (NC) contacts to the energized windings while applying normally open (NO) contacts to the un-energized windings, so that only useful power is consumed and no un-useful power is being consumed. In particular, relay114open circuits the 4-pole auxiliary winding106when energizing the 2-pole auxiliary winding108B and the shared auxiliary winding108A in the 2-pole configuration. Similarly, relay114open circuits the 2-pole auxiliary winding108B when energizing the 4-pole auxiliary winding106and the shared auxiliary winding108A in the 4-pole configuration. Thus, the switching circuit including relay114isolates the portion of the auxiliary winding108B when energizing the 4-pole auxiliary winding106and the shared portion of the auxiliary winding108A, in the 4-pole configuration. Relay114also isolates the portion of the auxiliary winding106when energizing the 2-pole auxiliary winding108B and the shared portion of the auxiliary winding108A, in the 2-pole configuration.

In copper windings, because the 2-pole auxiliary winding108B uses larger diameter wire than the diameter of the 4-pole auxiliary winding106, the copper loss in the shared auxiliary winding108A is reduced. In addition to the better performance efficiency, embodiments of the invention reduce the active material, e.g., the wire cost, in the 4-pole main winding104. As a result, the 4-pole main winding104uses less copper than the 4-pole auxiliary winding106. Sharing the auxiliary winding108A in both the 2-pole and 4-pole configurations saves more active material than sharing the 4-pole main winding from either the 2-pole main winding or the 2-pole auxiliary winding.

As noted above, the 2-pole main winding102is in the bottom of the slots308and the 4-pole main winding104is at the top of the slots308. The shared auxiliary winding108A is in the middle of the slots308. Locating the 4-pole main winding104at the top of the slots helps improve the 4-pole efficiency.

For both 2-pole and 4-pole configurations, the main windings102,104and their auxiliary windings108,106, respectively, have 90 degree phase shift or a 90 degree electrical angle in space with each other. This approach allows the use of only 2 single-pole double-throw switches, one in the relay114and one in an external control circuit connected to the connector202. In other words, the invention uses the same number of switches are 2/4 pole motors in the prior art. No additional internal switches to the motor or additional external control switches are needed for switching between pole configurations.

In view of the above, it will be seen that several advantages of the invention are achieved and other advantageous results attained.