CN110798122A

CN110798122A - Motor system and household electrical appliance

Info

Publication number: CN110798122A
Application number: CN201910950748.0A
Authority: CN
Inventors: 吕继方; 侯俊峰; 钟贵烈; 胡建
Original assignee: Midea Group Co Ltd; Guangdong Midea White Goods Technology Innovation Center Co Ltd
Current assignee: Midea Group Co Ltd; Guangdong Welling Motor Manufacturing Co Ltd; Guangdong Midea White Goods Technology Innovation Center Co Ltd
Priority date: 2019-10-08
Filing date: 2019-10-08
Publication date: 2020-02-14

Abstract

The application discloses electric machine system includes: the motor is provided with a bearing, a driving circuit and an isolated power supply. The driving circuit is connected with the motor and used for driving the motor. The isolation power supply is connected with the drive circuit and used for isolating the external power supply, generating a power supply based on the external power supply and outputting the power supply to the drive circuit. Through the mode, the electric corrosion of the motor bearing can be improved.

Description

Motor system and household electrical appliance

Technical Field

The application relates to the field of motors, in particular to a motor system and household electrical appliance.

Background

At present, many devices such as air conditioners, refrigerators and the like need to rely on motors to realize work. During the operation of the motor, the rotating shaft of the rotor generates a shaft voltage. Because the rotor of the motor is fixed by the bearing, when the shaft voltage is greater than a certain value, the bearing is subjected to insulation breakdown, so that the current flows through the bearing, the electric corrosion is generated, the service life of the bearing is shortened, and the motor cannot normally operate in severe cases.

Disclosure of Invention

The technical problem that this application mainly solved provides a motor system and tame electric installation, can alleviate the galvanic corrosion of motor bearing through reducing axle voltage.

In order to solve the technical problem, the application adopts a technical scheme that: there is provided an electric motor system comprising: a motor provided with a bearing; the driving circuit is connected with the motor and used for driving the motor; and the isolation power supply is connected with the drive circuit and used for isolating the external power supply, generating a power supply based on the external power supply and outputting the power supply to the drive circuit.

Wherein the bearing is grounded via impedance.

The isolation power supply comprises an input ground end and an output ground end, wherein the input ground end is used for being connected with a ground wire; the output ground end is electrically connected with the bearing so as to lead the bearing to be grounded through the impedance between the output ground end and the input ground end; alternatively, the motor system further comprises an impedance element through which the bearing is grounded, wherein a reference ground to which the impedance element is connected is the same as a reference ground to which the input ground of the isolated power supply is connected.

Wherein, the impedance element comprises at least one of a resistor, a capacitor and an inductor.

The motor further comprises a first shell connected with the bearing, and the bearing is electrically connected with the bearing through the first shell or is connected with the impedance element through the first shell.

Wherein, first shell is the end cover of motor.

The isolation power supply is a first isolation transformer.

The motor system further comprises a second isolation transformer, a power input end of the second isolation transformer is connected to an output end of the driving circuit, a power output end of the second isolation transformer is connected to the motor, and the second isolation transformer is used for isolating a first driving signal output by the driving circuit, generating a second driving signal based on the first driving signal, and outputting the second driving signal to the motor so as to drive the motor.

The driving circuit is provided with a second shell, and the second shell is grounded or not grounded; the driving circuit is a pulse width modulation power driving module.

In order to solve the above technical problem, another technical solution adopted by the present application is: a household appliance is provided, which comprises the motor system.

Compared with the prior art, the beneficial effects of this application are: through in motor system, add the isolation power, can keep apart motor and external power supply, avoid external power supply's interference noise to motor system's influence, and then provide the power supply behind the isolation external noise for drive circuit to can reduce the common mode voltage that drive circuit produced through keeping apart the power, and then reduce the axle voltage on the motor bearing. After the shaft voltage is reduced, the probability that the oil film of the bearing is broken down can be reduced, and the problem of electric corrosion of the bearing is solved. Moreover, even if the oil film of the bearing is broken down, the corresponding discharge current is reduced because the shaft voltage is reduced by adding the isolation power supply, so that the electric corrosion of the bearing can be reduced, and the effect of improving the electric corrosion problem is achieved.

Drawings

FIG. 1 is a schematic circuit diagram of an embodiment of the motor system of the present application;

FIG. 2 is a schematic view of an electric machine described in an embodiment of the present application;

FIG. 3 is another schematic view of a motor described in an embodiment of the present application;

FIG. 4 is a schematic circuit diagram of another embodiment of the motor system of the present application;

FIG. 5 is a schematic circuit diagram of a third embodiment of the motor system of the present application;

fig. 6 is a schematic structural diagram of an embodiment of a home appliance according to the present application.

Detailed Description

The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are only a part of the embodiments of the present application, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.

The terms "first", "second" and "third" are used herein for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. The term "and/or" herein is merely an association describing an associated object, meaning that three relationships may exist, e.g., a and/or B, may mean: a exists alone, A and B exist simultaneously, and B exists alone. In addition, the character "/" herein generally indicates that the former and latter related objects are in an "or" relationship. Further, the term "plurality" herein means two or more than two.

As shown in fig. 1, the motor system described in the embodiment of the motor system of the present application includes: an isolated power supply 30, a drive circuit 20 and a motor 10 with a bearing 12 are connected in sequence.

The isolation power supply 30 is used to isolate the external power supply 60, thereby isolating the interference noise of the external power supply 60, and to provide a power supply to the driving circuit 20 based on the external power supply 60, which is filtered out of the interference noise. The isolation power supply 30 can generate a power supply by using the external power supply 60, and isolate the external power supply 60 from the power supply, thereby filtering the external power supply 60 and generating a pure power supply. In a specific application, the isolation power supply 30 includes a first isolation transformer, two power input terminals 33 of the first isolation transformer are respectively connected to the live line and the neutral line (as the external power supply 60), and the first isolation transformer isolates the external voltage signal input by the external power supply 60 and generates an induced electromotive force, i.e. a power supply, and then outputs the induced electromotive force to the driving circuit 20 through two power output terminals 34 of the first isolation transformer. Further, the first isolation transformer may form a power topology with other electronic components, such as a Buck-Boost topology, a Boost-Boost topology, or a Buck-Boost-Buck topology. It will be appreciated that the isolated power source described in this embodiment may be any electronic component or circuit that can implement the isolation of the external power source 60 from the power supply. So long as the electronic components or circuits that isolate the two power sources from each other are implemented are consistent with the isolated power sources described herein.

The driving circuit 20 is used for driving the motor 10 to work. Specifically, after the isolated power supply 30 outputs the power supply, the driving circuit 20 generates a first driving signal to drive the motor 10 to operate. The driving circuit 20 may include an input terminal 23 and an output terminal 22, and the driving circuit 20 inputs the power supply signal through the input terminal 23, generates the first driving signal, and outputs the first driving signal through the output terminal 22 to drive the motor 10 to rotate. Specifically, the driving circuit 20 may be a Pulse Width Modulation (PWM) driving module. The pwm power driving module may output a series of pulse signals with equal amplitude to make the motor 10 generate an alternating magnetic field to drive the rotor 14 to rotate, so that the motor 10 can work normally. For example, after the driving signal output by the pwm power driving module is transmitted to the motor 10, an alternating magnetic field may be generated in the motor 10.

The motor 10 may generate an alternating magnetic field after receiving the first driving signal, so that the rotor 14 rotates and the motor 10 operates. In the present embodiment, the motor 10 may be, but is not limited to, a brushless motor, such as a dc brushless motor. Specifically, referring to fig. 2 in combination, the motor 10 includes a first housing 11, a bearing 12, a stator 13, and a rotor 14, and the rotor 14 includes a rotation shaft 141. The rotation shaft 141 is coupled to the bearing 12 such that the rotation shaft 141 rotates the rotor 14 supported by the bearing 12. During the operation of the motor 10, the rotor 14 may generate a shaft voltage, which is also present at the bearing 12 because the rotor 14 is connected to the bearing 12 through the rotating shaft 141, and thus there is a problem that the shaft voltage is excessively high, which causes electric corrosion of the bearing.

In this embodiment, when the driving circuit 20 outputs the driving signal, it also outputs a common mode voltage, and the common mode voltage can be conducted to the stator 13 through the conducting wire, and further generates a shaft voltage on the rotating shaft 141 of the rotor 14 through the electrostatic capacitive coupling of the gap between the stator 13 and the rotor 14 of the motor 10. In this embodiment, the isolation power supply 30 is added to the motor system, so that the common mode voltage output by the driving circuit 20 can be reduced, and the shaft voltage generated on the rotating shaft 141 of the rotor 14 can be reduced. When the shaft voltage can be effectively reduced, the probability of the bearing 12 being broken down can be reduced, and the probability that the current flows through the bearing 12 due to the breakdown is further reduced, that is, the condition that the bearing 12 is corroded by the current is avoided, so that the problem of the corrosion of the bearing 12 can be solved. Moreover, even if the shaft voltage on the rotating shaft 141 of the rotor 14 is too large, the shaft voltage can be reduced because of the addition of the isolation power supply 30 when the bearing 12 is broken down, so that the current flowing through the bearing 12 on the rotating shaft 141 of the rotor 14 is correspondingly reduced, and the problem that the bearing 12 is subjected to electrical corrosion because of breakdown is solved.

Referring to fig. 2 and 3, in the present embodiment, the bearing 12 may be electrically connected to the first housing 11, and the first housing 11 may be, but is not limited to, an end cover 111 of the motor 10. By electrically connecting the bearing 12 and the first housing 11, the current flowing through the bearing 12 can be conducted to other places through the first housing 11, so as to achieve the effect of guiding the current to flow.

Specifically, the bearing 12 may be, but is not limited to, a rolling bearing 12. With continued reference to fig. 3, for example, the rolling bearing 12 includes an inner ring 121, an outer ring 122, and rolling bodies 123. The inner ring 121 and the outer ring 122 of the rolling bearing 12 are connected by rolling elements 123, and an oil film (not shown) lubricates the rolling elements 123 and the inner ring 121 and the outer ring 122, and insulates the inner ring 121 and the outer ring 122 from each other. The rolling bearing 12 is connected to the first housing 11, for example, by fixedly connecting the outer ring 122 of the rolling bearing 12 to the first housing 11, wherein the outer ring 122 of the rolling bearing 12 may be fixedly connected to the first housing 11 by press fitting, heat fitting, or the like. The outer ring 122 of the rolling bearing 12 may be electrically connected to the first housing 11. For the embodiment in which the outer ring 122 of the rolling bearing 12 and the first housing 11 are both made of metal, when they are in contact, an electrical connection is achieved. The rolling bearing 12 and the rotating shaft 141 of the rotor 14 may be fixed by fixedly connecting the inner ring 121 of the rolling bearing 12 and the rotating shaft 141 of the rotor 14, and simultaneously electrically connecting the rotating shaft 141 of the rotor 14 and the inner ring 121 of the rolling bearing 12, wherein the rotating shaft 141 of the rotor 14 may be fixedly connected to the inner ring 121 of the rolling bearing 12 by press fitting, heat fitting, or the like. For the embodiment in which the rotating shaft 141 of the rotor 14 and the inner ring 121 of the rolling bearing 12 are both made of metal, electrical connection is achieved when the rotating shaft 141 and the inner ring 121 are in direct contact.

By fixedly and electrically connecting the outer ring 122 of the rolling bearing 12 with the first housing 11 of the motor 10, when current flows through the outer ring 122 of the rolling bearing 12, the current can flow to other places through the first housing 11, and the electrical connection between the two has the effect of guiding the current flow. Similarly, by electrically connecting the rotating shaft 141 of the rotor 14 and the inner ring 121 of the rolling bearing 12, when a current flows through the rotating shaft 141 of the rotor 14, the current can flow from the inner ring 121 to other places, thereby achieving an effect of guiding the current.

When the bearing 12 is the rolling bearing 12, the oil film in the rolling bearing 12 is broken down due to the overlarge shaft voltage, so that the inner ring 121 and the outer ring 122 of the rolling bearing 12 are not insulated any more, and at this time, the current generated by the shaft voltage flows to the outer ring 122 through the inner ring 121 of the rolling bearing 12, so that the rolling bearing 12 is subjected to electric corrosion. Because the isolation power supply 30 is added, the common mode voltage output by the driving circuit 20 can be reduced, the shaft voltage is further reduced, the probability that an oil film is broken down is reduced, and the problem of electric corrosion of the rolling bearing 12 is solved. When the oil film is broken down, the shaft voltage can be reduced by adding the isolated power supply 30, so that the current flowing from the inner ring 121 to the outer ring 122 of the rolling bearing 12 is reduced, and the electric corrosion of the rolling bearing 12 is reduced.

To further ameliorate the problem of electrical corrosion of the bearing, the bearing 12 may be impedance grounded, so that when the shaft voltage is too high to break down the bearing 12, the current generated from the shaft 141 in the rotor 14 may flow through the bearing 12 to the impedance and then to the ground. By connecting the bearing 12 of the motor 10 to the impedance and grounding, when the bearing 12 is broken down, the voltage inside the bearing 12 can be reduced by utilizing impedance voltage division, and further, the current flowing through the bearing 12 can be reduced, thereby achieving the effect of reducing the electric corrosion. Meanwhile, since the grounding reference point in the circuit system is changed by grounding the bearing 12 through impedance, the common mode voltage output by the driving circuit 20 is correspondingly reduced, so that the effect of reducing the shaft voltage is achieved, the current flowing through the bearing 12 is reduced, and the electric corrosion of the bearing 12 is reduced.

When the bearing 12 is a rolling bearing 12, the oil film of the rolling bearing 12 is broken by the excessive shaft voltage, and the current is grounded via the inner ring 121, the outer ring 122 and the impedance through the rotating shaft 141 of the rotor 14. The impedance grounding can also change the grounding reference point of the circuit system at the moment, and the effect of reducing the shaft voltage is achieved. Meanwhile, when the bearing is grounded through impedance, impedance partial pressure can be utilized, and due to the effect, the current flowing from the inner ring 121 to the outer ring 122 of the rolling bearing 12 can be reduced through grounding and increasing the impedance partial pressure, so that the electric corrosion of the bearing is improved.

An embodiment in which the bearing 12 is impedance grounded is described in detail below in conjunction with fig. 4 and 5.

Referring to fig. 4, the motor system includes the isolated power supply 30, the drive circuit 20, and the motor 10 as described in fig. 1. In this embodiment, the isolated power supply 30 further includes an input ground 31 and an output ground 32. The bearing 12 is grounded via an impedance 35 between the output ground 32 and the input ground 31 of the isolated power supply 30 to achieve grounding of the bearing 12 via the impedance 35.

Specifically, the input ground terminal 31 is used for grounding, such as connecting to a ground line 70. The output ground 32 is electrically connected to the bearing 12, for example, the output ground 32 is directly electrically connected to the bearing 12 or indirectly electrically connected to the bearing 12, and the indirect electrical connection may be that the output ground 32 is connected to a component electrically connected to the bearing 12, so as to achieve an indirect electrical connection with the bearing 12 through the component. In the present embodiment, the bearing 12 of the motor 10 is electrically connected to the first housing 11, so that the output ground 32 can be directly connected to the first housing 11. In a specific application, the first housing 11 is an end cover 111 of the motor 10, so the output ground terminal 32 can be directly connected to the end cover 111 of the motor 10.

By electrically connecting the bearing 12 to the first housing 11, the current flowing through the bearing 12 can be conducted to the impedance 35 between the output ground 32 and the input ground 31 of the isolated power supply 30 through the first housing 11, and the ground 70 is connected to the input ground 31 of the isolated power supply 30, thereby achieving grounding. By establishing the grounding loop, the grounding point of the circuit system can be changed, and the common mode voltage output by the driving circuit 20 can be reduced, thereby reducing the shaft voltage. Meanwhile, the impedance 35 connected by the ground loop can realize voltage division and reduce the shaft voltage. This reduces the current flowing through the bearing 12, and improves the problem of galvanic corrosion of the bearing 12.

Referring to fig. 5, the motor system includes the isolated power supply 30, the drive circuit 20, and the motor 10 as described in fig. 1. In this embodiment, the isolated power supply 30 further comprises an input ground terminal 31, and the motor system further comprises an impedance element 40. The impedance element 40 may be at least one of a resistor, a capacitor, and an inductor.

The bearing 12 is grounded via the impedance element 40. Specifically, one end of the impedance element 40 is grounded, and the reference ground to which one end of the impedance element 40 is connected is the same as the reference ground to which the input ground terminal 31 of the isolated power supply 30 is connected. The other end of the impedance element 40 is electrically connected to the bearing 12, for example, directly or indirectly electrically connected to the bearing 12, and the indirect electrical connection may be that the other end of the impedance element 40 is connected to an element electrically connected to the bearing 12, so as to achieve an indirect electrical connection with the bearing 12 through the element. In the present embodiment, the bearing 12 of the motor 10 is electrically connected to the first housing 11, so that the other end of the impedance element 40 can be directly connected to the first housing 11. In a specific application, the first housing 11 is an end cap 111 of the motor 10, so that the other end of the impedance element 40 can be directly connected to the end cap 111 of the motor 10.

The bearing 12 is electrically connected to the first housing 11, so that the current flowing through the bearing 12 can be also conducted to the impedance element 40 through the first housing 11 and then grounded, and the reference ground connected to the impedance element 40 is set to be the same as the reference ground connected to the input ground terminal 31 of the isolated power supply 30. By establishing the grounding loop, the grounding point of the circuit system can be changed, and the common mode voltage output by the driving circuit 20 can be reduced, thereby reducing the shaft voltage. Meanwhile, the impedance element 40 connected by the ground loop can realize voltage division and also can reduce the shaft voltage. This reduces the current flowing through the bearing 12, and improves the problem of galvanic corrosion of the bearing 12.

In another embodiment, to further improve the problem of electrical corrosion of the bearings, an isolation transformer may be provided at the output 22 of the driving circuit 20. With continued reference to fig. 4, the motor system 100 includes a second isolation transformer 50 in addition to the isolated power supply 30, the drive circuit 20, and the motor 10 as described in fig. 1. The power input 51 of the second isolation transformer 50 is connected to the output 22 of the driving circuit 20, and the power output 52 of the second isolation transformer 50 is connected to the motor 10. The second isolation transformer 50 is configured to isolate the first driving signal output by the driving circuit 20, generate a second driving signal based on the first driving signal, and output the second driving signal to the motor 10 to drive the motor 10. The power input 51 of the second isolation transformer 50 may be connected to the output 22 of the driving circuit 20 through a metal wire, and the power output 52 of the second isolation transformer 50 may be connected to the motor 10 through a metal wire.

In this embodiment, by adding the second isolation transformer 50 between the driving circuit 20 and the motor 10, the second isolation transformer 50 can be used to isolate the first driving signal generated by the driving circuit 20, so as to achieve the function of filtering the power supply. Meanwhile, the added second isolation transformer 50 can also play a role in reducing the common-mode voltage output by the driving circuit 20, so that the shaft voltage can be correspondingly reduced, and the effect of reducing the electric corrosion of the bearing 12 can be realized by reducing the shaft voltage.

It will be appreciated that in the embodiment shown in fig. 1 and 5, a second isolation transformer 50 may be added between the drive circuit 20 and the motor 10 as required.

In the above embodiment, the driving circuit 20 may be provided with the second housing 21, and the second housing 21 may be grounded or ungrounded (i.e. floating) according to actual requirements. As shown in fig. 2, the second housing 21 may be grounded to increase the grounding point in the circuit system, and further reduce the common mode voltage output by the driving circuit 20, thereby reducing the shaft voltage and alleviating the electrical corrosion. Of course, as shown in fig. 1, the second housing 21 of the driving circuit 20 may not be grounded.

Referring to fig. 6, fig. 6 is a schematic structural diagram of an embodiment of a home appliance according to the present application. In this embodiment, the household electrical appliance 110 includes the motor system 100 described in the above embodiments of the motor system 100 of the present application. For a detailed description of the motor system 100, reference is made to the above description of the motor system 100 in the embodiments of the motor system of the present application.

Specifically, the home appliance 110 may be a refrigerator, an air conditioner, a washing machine, or the like.

Above-mentioned scheme, through in motor system, add the isolation power supply, can keep apart motor and external power supply, avoid external power supply's interference noise to motor system's influence, and then provide the power supply after keeping apart the external noise for drive circuit to can reduce the common mode voltage that drive circuit produced through keeping apart the power supply, and then reduce the axle voltage on the motor bearing. After the shaft voltage is reduced, the probability that the oil film of the bearing is broken down can be reduced, and the problem of electric corrosion of the bearing is solved. Moreover, even if the oil film of the bearing is broken down, the corresponding discharge current is reduced because the shaft voltage is reduced by adding the isolation power supply, so that the electric corrosion of the bearing can be reduced, and the effect of improving the electric corrosion problem is achieved.

The above description is only an example of the present application and is not intended to limit the scope of the present application, and all modifications of equivalent structures and equivalent processes, which are made by the contents of the specification and the drawings, or which are directly or indirectly applied to other related technical fields, are intended to be included within the scope of the present application.

Claims

1. An electric machine system, comprising:

a motor provided with a bearing;

the driving circuit is connected with the motor and used for driving the motor;

and the isolation power supply is connected with the drive circuit and used for isolating an external power supply, generating a power supply based on the external power supply and outputting the power supply to the drive circuit.

2. The system of claim 1, wherein the bearing is impedance grounded.

3. The system of claim 2, wherein the isolated power supply comprises an input ground and an output ground, the input ground for connection to a ground line;

the output ground is electrically connected with the bearing so that the bearing is grounded through impedance between the output ground and the input ground; alternatively, the motor system further comprises an impedance element through which the bearing is grounded, wherein a reference ground to which the impedance element is connected is the same as a reference ground to which an input ground of the isolated power supply is connected.

4. The system of claim 3, wherein the impedance element comprises at least one of a resistor, a capacitor, and an inductor.

5. The system of claim 3, wherein the motor further comprises a first housing coupled to the bearing, the bearing being electrically coupled to the bearing via the first housing, or the bearing being coupled to the impedance element via the first housing.

6. The system of claim 5, wherein the first housing is an end cap of the electric machine.

7. The system of claim 1, wherein the isolated power supply comprises a first isolation transformer.

8. The system of claim 1, further comprising a second isolation transformer, a power input of the second isolation transformer being connected to the output of the driving circuit, a power output of the second isolation transformer being connected to the motor, the second isolation transformer being configured to isolate the first driving signal output by the driving circuit, generate a second driving signal based on the first driving signal, and output the second driving signal to the motor to drive the motor.

9. The system of claim 1, wherein the drive circuit is provided with a second housing, the second housing being grounded or the second housing being ungrounded;

the driving circuit is a pulse width modulation power driving module.

10. An electric household appliance comprising an electric machine system according to any one of claims 1 to 9.