DE112010004128T5 - Single-phase AC induction motor, apparatus for operating a single-phase AC induction motor and compressor with such a motor or device - Google Patents

Abstract

The invention relates to a single-phase AC induction motor with a main winding and an auxiliary winding. The motor has a switch for short-circuiting a running capacitor. To achieve variable running capacity, the motor has an additional running capacitor that is used in series with the other running capacitor, and the switch shorts one of the capacitors.

Description

INTRODUCTION

The invention relates to a single-phase AC induction motor having a main winding and an auxiliary winding. In particular, the invention relates to an induction motor having a first connection structure for connecting the main winding between a supply phase and a ground of the power supply and a second connection structure for connecting the auxiliary winding between the supply phase and a ground of the power supply.

BACKGROUND OF THE INVENTION

Single-phase AC induction motors with a relay for activating or deactivating a running capacitor during operation.

A single-phase motor is a lathe having both a main winding and an auxiliary winding and a squirrel-cage rotor. The most common types of single-phase motors are: auxiliary phase, capacitor start, capacitor run and capacitor start / capacitor run. If both a main winding and an auxiliary winding are present, the single-phase machine can be operated as a two-phase machine.

Often the motors are connected to a power supply via a relay, the relay activating or inactivating the running capacitor during operation.

In a known motor, the above-mentioned second connection structure includes first and second paths extending in parallel between the supply phase and the auxiliary winding. The first of these two paths comprises a running capacitor and the second path may comprise a variable resistor, e.g. A PTC. A relay function inhibits electrical conductivity in the second path unless the current in the main winding exceeds a certain limit, and the second path is therefore conductive only when the motor consumes a relatively high current.

DESCRIPTION OF THE INVENTION

It is an object of embodiments of this invention to provide an improved engine and apparatus for operating an engine.

Accordingly, in a first aspect, the invention provides a single-phase AC induction motor having a main winding, an auxiliary winding, a first connection structure for connecting the main winding between a supply phase and the ground of a power supply, and a second connection structure for connecting the auxiliary winding between the supply phase and the ground of the power supply, the second connection structure having first and second paths extending in parallel between the supply phase and the auxiliary winding, the first path having a running capacitor and the second path having a resistance, the motor further comprising a switch incorporated in permitting conduction in the second path in a closed state and inhibiting conduction in the second path in an open state, the switch being movable between the open and closed states, depending on a current in the first turn characterized in that the second connection structure additionally comprises a further running capacitor in series with the running capacitor in the second path and a bridge connecting the paths between the first and second connection points, the first connection point being between the switch and the resistor and second connection point between the running capacitor and the other running capacitor.

Because of the further run capacitor and the corresponding bridge, the auxiliary winding is powered by a set of two series running capacitors when the switch is in the open state.

According to a well-established capacitor theory, two capacitors in series deliver a capacity that is lower than the capacitance of at least one of the capacitors. If z. For example, if each run capacitor has a capacitance of 4 μF, the comparable capacitance of the two capacitors connected in series becomes 2 μF. Accordingly, the motor can vary its running capacity depending on the current drawn from the main winding, which current activates or inactivates the relay.

The result is a load-dependent efficiency. A high load results in a high capacitor value and thus an adapted high efficiency. A low load results in a low capacitor value, which is optimal for the low load situation, and provides high efficiency.

When the load is high, the torque of the motor increases at the same time, which is advantageous especially at high load. This feature is already patented, but in a version where capacitors are connected in parallel, creating the need for a different relay design.

In the present context, "a first terminal structure" refers to a structure of conductors for connecting the main winding between a supply phase and grounding of a power supply.

"A second connection structure" in this context refers to a structure of conductors for connecting the auxiliary winding between a supply phase and grounding of a power supply. The structure may share the conductors with the first connection structure, with some electrically conductive elements being part of both the first and second connection structures.

"First and second paths" in this context refer to conductive paths that are part of the second connection structure. In particular, the second path can also form part of the first connection structure. As said, the first and second paths extend in parallel between the supply phase and the auxiliary winding, i. H. the auxiliary winding may be powered by one or both of the first and second paths, depending on the state of the switch. The motor can also have additional paths.

"Running capacitor" here refers to any type of capacitor that is suitable for operating the motor.

"Starting capacitor" here means any type of capacitor that is suitable for starting the engine.

"Resistance" refers to a component that provides an ohmic resistance. The resistor according to the invention may in particular be a variable resistor.

"Variable resistance" here refers to a resistance that can vary, e.g. Depending on the current flowing through the resistor or the temperature of the resistor, or a resistance that changes due to the duration of a period of time. A PTC is an example of a variable resistor because it raises the resistance at elevated temperature, but other resistors can be selected.

"A switch" herein refers to any type of structure that has at least two states, allowing conductivity in the second path in one of the states and inhibiting in the other state. The switch may be a conventional switch, or may be part of a relay, e.g. B. a transistor-based relay. Accordingly, the phrase "the switch is movable" may mean large movements of a switching element in relation to contact points, or may involve microscopic switching, e.g. B. in a CPU, etc. mean.

"A bridge" here refers to a conductive connection between the first and the second path. If the resistance in the second path is large, the motor may be powered by the running capacitor when the switch is closed and by the additional running capacitor in series with the running capacitor when the switch is open.

In accordance with the invention, the first connection structure may form a coil which can generate a magnetic field due to conduction of a current in the first connection structure, the coil being arranged relative to the switch so that the state can be changed by means of the magnetic field such that the state of the switch depends on the current in the first connection structure.

Integrating the coil into the second path provides another advantage because the additional run capacitor can thereby be discharged across the coil when the switch is moved from open to closed just as the additional run capacitor is being charged. In this regard, the switch may preferably be disposed in the second path between the coil and the bridge such that the switch only affects the current between the coil and the auxiliary winding.

For discharging the additional run capacitor in a controlled manner, the motor may include an additional resistor disposed in the second path between the supply phase and the switch. In this case, the above-mentioned coil does not necessarily have to be arranged in the second path, since the energy discharged from the additional capacitor is absorbed by the additional resistor. As an alternative to the coil or additional resistor, the second path may use any type of suitable current consumer to discharge the additional capacitor when the switch moves to the closed state, e.g. B. a coil or a conventional resistor.

The motor may also include an additional switch for enabling conductivity in the second path in a closed state and for inhibiting conduction in the second path in an open state, the additional switch being responsive to a current in the first connection structure is movable between the open and the closed state, and wherein the additional switch is arranged in the second path between the bridge and the resistor. In this case, the additional switches in its open state prevent current through the resistor while allowing conductivity in the first part of the second path from the supply phase through the bridge to the first path.

The first connection structure may form an additional coil which may generate a magnetic field due to a conduction of current in the first connection structure, the additional coil being arranged relative to the additional switch such that the state of the additional switch is by use of the additional one Coil generated magnetic field can be changed.

In order to secure the power consumption for discharging the additional capacitor, the second path may also have the additional coil.

In addition to the two running capacitors, the motor may also have a starting capacitor, which is arranged in the second path between one of the switches and the auxiliary winding. The start capacitor provides an increased moment at startup. At the start, d. H. before increasing the PTC temperature, conduction through the PTC and the starting capacitor increases the starting torque, and the PTC turns off the current as its temperature rises, so that the increased starting torque ends.

In a second aspect, the invention provides an apparatus for operating a single-phase AC induction motor having a main winding and an auxiliary winding. The device according to the second aspect comprises a first connection structure for connecting the main winding between a supply phase and ground of a power supply, and a second connection structure for connecting the auxiliary winding between the supply phase and ground of the power supply, wherein the second connection structure has first and second paths extending extending in parallel between the supply phase and the auxiliary winding, wherein the first path has a running capacitor and the second path has a resistance, and the device further comprises a switch which allows conductivity in the second path in a closed state and conductivity in the second path in an open state prevents, wherein the switch in response to a current in the first connection structure between the open and the closed state is movable, characterized in that the second connection structure, an additional running capacitor in series with the Laufkon capacitor in the second path, and a bridge ( 12 ) for connecting the paths between the first and second connection points, wherein the first connection point between the switch and the resistor and the second connection point between the running capacitor and the additional running capacitor.

The device may additionally have any of the features described in connection with the first aspect of the invention.

In a cooling system, it is common that the load on the compressor depending on z. B. meteorological conditions or depending on units that are arranged in the cooling system or removed from the cooling system changes. The burden therefore changes in an unpredictable way. In a third aspect, the invention provides a compressor provided with a motor or a device as described above. The compressor can be used in particular in a cooling system.

Since the device and the motor are capable of automatically changing the capacity depending on the load of the motor, a cooling system provided with such a device or motor can automatically adapt to the current load situation.

MORE DETAILED DESCRIPTION

Other uses of the present invention will become apparent from the following detailed description and specific examples. It should be understood, however, that the detailed description and specific examples which illustrate the invention are illustrative only, as various changes and modifications within the meaning and scope of the invention will become apparent to those skilled in the art from this detailed description.

1 shows a motor diagram of a motor according to the prior art;

2 shows a motor diagram of an engine according to the invention, and

3 - 8th show various alternative embodiments of a motor according to the invention.

As in 1 As shown, a conventional electric motor has a main winding 1 and an auxiliary winding 2 on. Both windings are over the line 4 with the zero terminal 3 connected to an AC power supply.

The main winding 1 is over the coil 6 with the supply phase 5 connected to the power supply.

The auxiliary winding 2 is about first and second parallel paths with the supply phase 5 connected. The first path includes a PTC 8th in series with a switch 9 , The desk 9 gets off the coil 6 operated, so he closes, if sufficient high current in the coil 6 flows. The second path includes a running capacitor 10 that is between the supply phase 5 and the auxiliary winding 2 connected.

In a starting situation, in which the main winding 1 consumes a high electric current, that is in the coil 6 generated magnetic field high enough to the switch 9 close, and the PTC 8th can therefore, depending on its temperature, current to the auxiliary winding 2 which thereby in the start mode the main winding 1 supported.

2 schematically shows a motor according to the invention. In the following, "the coil terminal 7 "Generally an optional arrangement of the terminal in an area between the main winding 1 and the coil 6 denote, ie the coil 6 is between the supply phase 5 and the coil terminal 7 ,

The auxiliary winding 2 is about first and second parallel paths with the supply phase 5 connected. The first path extending between the coil terminal 7 and the auxiliary winding 2 extends, includes a PTC 8th in series with a switch 9 ,

A first additional running capacitor 11 is arranged in the second path, so that the auxiliary winding 2 via two series-connected running capacitors with the supply phase 5 is connected.

A bridge 12 extends between a point in the first path between the switch 9 and the PTC 8th and a point in the second path between the running capacitor 10 and the first additional running capacitor 11 , This connects the bridge 12 the first path and the second path with each other.

In operation, the motor is turned on and the main winding consumes a relatively high current. The high current closes the switch 9 and the first additional running capacitor 11 is over the bridge 12 , the closed switch 9 and the coil 6 shorted. In this condition, the PTC is cold and its resistance is therefore relatively low, e.g. Between 5 and 25 ohms, and the auxiliary winding is therefore powered by the PTC.

In an example where both the running capacitor 10 as well as the first additional running capacitor 11 have a capacity of 4 μF, the auxiliary winding is thereby through the PTC 8th and a single 4 μF capacitor parallel to the PTC 8th provided.

When the engine is started, and the current is lowered to a level where the coil 6 no longer the switch 9 in the closed state, the opening of the switch activates the first additional running capacitor 11 and the auxiliary winding 2 is now supplied by two series-connected 4 μF capacitors, ie the resulting capacitance becomes 2 μF according to known capacitor theory.

Across the bridge 12 is the PTC 8th furthermore connected in parallel with one of the capacitors. In a normal running mode situation, however, the PTC becomes relatively hot, and therefore provides high resistance, e.g. B. several kilo-ohms, and the auxiliary winding 2 Therefore, in principle, only the two capacitors connected in series 10 . 11 provided.

3 shows an embodiment that in 2 similar, only it has an additional resistance structure 13 , and delivers z. As a capacitive, resistive or inductive resistor, or combinations thereof, so that the additional running capacitor 11 is discharged in a controlled manner using the resistor structure.

The in 2 and 3 shown PTC 8th is preferably an E-PTC to save power in run mode. In a conventional PTC, warming up the PTC causes unwanted energy loss, whereas using an E-PTC in this case will prevent energy loss by shutting off until the power is turned off.

4 shows an embodiment according to the embodiment in 2 with an additional switch 14 that of an additional coil 15 is operated. The desk 14 is placed in the first path so that the PTC 8th is switched off when the engine is no longer in start mode - ie when the current through the main winding is no longer sufficient to turn the switch 14 to keep in the closed state. In other words, the switch affects 14 only the start mode and shuts off when the run mode is reached. In this case, the start corresponds exactly to the one in 2 As shown, but when the start mode is completed and the motor is operated in run mode at rated speed, the auxiliary winding 2 powered only by the two capacitors connected in series. Again, each capacitor has a capacitance of 4 μF, with the resulting capacitance in run mode becoming 2 μF. The desk 9 and the corresponding coil 6 are designed to toggle between the two states while the engine is operating in run mode. Each time the engine is heavily loaded when running in run mode and the main winding 1 therefore consumes a high current, but not as high as in the start mode, the switch 9 closed and the additional running capacitor 11 is bypassed.

In the execution after 4 The motor also includes a heat-sensitive circuit breaker 16 in the pipe 4 to the zero connection 3 ,

5 shows an embodiment according to the of 3 but with a starting capacitor 17 who is in series with the PTC 8th is used. The starting capacitor increases the starting torque.

6 shows an embodiment according to the of 3 , In this case, however, the additional switch 14 and the extra coil 15 , in the 3 used to turn off the PTC in run mode, by a double switch structure 18 . 19 replaced by a single coil 6 is operated.

In start mode, the high current closes both switches and bypasses the additional run capacitor 11 and turns on the PTC 8th one. In run mode, the PTC 8th switched off and the additional running capacitor 11 is turned on. In addition, the second path now extends between the coil terminal 7 and the auxiliary winding 2 ie the running capacitor 10 and the additional running capacitor 11 are now between the coil connection 7 and the main winding 2 connected in rows. When the switch 19 closes, discharges the additional running capacitor 11 in a controlled way through the resistor 20 to avoid damage caused by too fast unloading.

7 shows an embodiment according to the of 6 However, the second path now extends between the supply phase 5 and the auxiliary winding 2 ie the running capacitor 10 and the additional running capacitor 11 are now between the supply phase 5 and the auxiliary winding 2 connected in rows. When the switch 19 closes, discharges the additional running capacitor 11 in a controlled manner through the coil 6 and damage to contact points of the switch 6 Too fast unloading will be avoided.

8th shows a motor in which the running capacitor 10 is arranged parallel to a path of the coil 6 , the switch 9 and the second additional running capacitor 25 between the supply phase 5 and the auxiliary winding 2 contains. In this case, the resulting capacitance corresponds to the parallel connection of the running capacitor 10 and the second additional running capacitor of the sum of the two capacitors 10 . 25 when the switch is closed, ie when the main winding consumes sufficient power around the switch 9 close.

Claims (11)

Single-phase AC induction motor with one main winding ( 1 ), an auxiliary winding ( 2 ), a first connection structure for connecting the main winding ( 1 ) between a supply phase ( 5 ) and the grounding of a power supply, and a second connection structure for connecting the auxiliary winding ( 2 ) between the supply phase ( 5 ) and grounding ( 3 ) of the power supply, the second connection structure having first and second paths extending between the supply phase and the auxiliary winding ( 2 ), wherein the first path is a running capacitor ( 10 ) and the second path is a resistor ( 8th ), the motor additionally having a switch ( 9 ), which in a closed state of the switch ( 9 ) allows a conductivity in the second path and in an open state of the switch ( 9 ) prevents conductivity in the second path, the switch ( 9 ) is movable between the open and closed states, depending on a current in the first connection structure, characterized in that the second connection structure additionally comprises a further running capacitor ( 11 ) in series with the running capacitor ( 10 ) in the second path and a bridge ( 12 ), which connects the paths between first and second connection points, wherein the first connection point between the switch ( 9 ) and the resistance ( 8th ) and the second connection point between the running capacitor ( 10 ) and the further running capacitor ( 11 ). Motor according to Claim 1, in which the first connection structure comprises a coil ( 6 ) which is capable of generating a magnetic field due to conduction of current in the first connection structure, the coil being biased relative to the switch (10). 9 ) is arranged so that the state of the switch can be changed using the magnetic field. Motor according to Claim 2, in which the second path is the coil ( 6 ). Motor according to claim 3, in which the switch ( 9 ) in the second path between the coil ( 6 ) and the bridge ( 12 ) is arranged. Motor according to one of the preceding claims, comprising an additional resistor ( 13 ) in the second path between the supply phase ( 5 ) and the switch ( 9 ) is arranged. Motor according to one of the preceding claims, comprising an additional switch ( 14 ) provided to enable conductivity in the second path in a closed state of the switch and to prevent conduction in the second path in an open state of the switch, the additional switch intervening the open and closed states, depending on a current in the first terminal structure, wherein the additional switch ( 14 ) in the second path between the bridge ( 12 ) and the resistance ( 8th ) is arranged. Motor according to Claim 6, in which the first connection structure comprises an additional coil ( 15 ), which generates a magnetic field due to a conduction of current in the first connection structure, the additional coil ( 15 ) in relation to the additional switch ( 14 ) is arranged so that the state of the additional switch using the from the additional coil ( 15 ) generated magnetic field can be changed. Motor according to claim 7, in which the second path is the additional coil ( 15 ). Motor according to one of the preceding claims, the additional one running capacitor ( 17 ) located in the second path between one of the switches ( 9 . 14 ) and the auxiliary winding is arranged. Device for operating a single-phase AC induction motor with a main winding ( 1 ) and an auxiliary winding ( 2 ), wherein the device has a first connection structure for connecting the main winding between a supply phase ( 5 ) and grounding ( 3 ) of a power supply, and a second connection structure for connecting the auxiliary winding ( 2 ) between the supply phase ( 5 ) and grounding ( 3 ) of the power supply, the second connection structure having first and second paths extending between the supply phase ( 5 ) and the auxiliary winding ( 2 ), wherein the first path is a running capacitor ( 10 ) and the second path is a resistor ( 8th ), the device additionally having a switch ( 9 ), which in a closed state of the switch ( 9 ) allows a conductivity in the second path and in an open state of the switch ( 9 ) prevents conductivity in the second path, the switch ( 9 ) is movable between the open and closed states, depending on a current in the first connection structure, characterized in that the second connection structure additionally comprises a further running capacitor ( 11 ) in series with the running capacitor ( 10 ) in the second path and a bridge ( 12 ), which connects the paths between first and second connection points, wherein the first connection point between the switch ( 9 ) and the resistance ( 8th ) and the second connection point between the running capacitor ( 10 ) and the further running capacitor ( 11 ). Compressor with a motor according to claims 1 to 9 or a device according to claim 10.

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