Switching device of motor, control method of switching device, compressor and air conditioner

Abstract

The invention discloses a switching device of a motor, a compressor, an air conditioner and a control method of the switching device of the motor. The switching device comprises a first switch group and a second switch group, the first end of the first switch group is connected with the second end of the first set of windings, and the second end of the first switch group is connected with the first end of the first set of windings; the selection end of the first switch group is connected with the first end of the second winding, and the second end of the second winding is connected to form a center point; the second switch group is connected between the second ends of two adjacent phases of windings of the first set of windings; and the connection mode between the first set of windings and the second set of windings is switched by controlling the on-off conditions of the first switch group and the second switch group. According to the scheme, the connection modes of the two windings of the motor are switched, so that the impact on a power grid and the motor when the motor is started is reduced, the motor is started more quickly and stably, the starting reliability of the motor is improved, and the running range of the motor is widened.

Description

Technical Field

[0001] The present invention belongs to the technical field of motors, and specifically relates to a motor switching device and a control method thereof, a compressor and an air conditioner, and more particularly to a motor winding series-parallel switching device and a control method thereof, a compressor and an air conditioner. Background Art

[0002] In recent years, motors have been developing towards high speed and high efficiency. High speed can increase the power density of motors and reduce manufacturing costs. However, in related solutions, the impact on the power grid and motors when the motors are started under heavy load is large, and it is impossible to ensure that the motors start quickly and smoothly, which affects the reliability of motor starting.

[0003] The above contents are only used to assist in understanding the technical solution of the present invention and do not constitute an admission that the above contents are prior art. Summary of the invention

[0004] The object of the present invention is to provide a switching device for a motor, a compressor and an air conditioner and a control method for the switching device of their motor, so as to solve the problem in related schemes that when the motor is started under heavy load, the impact on the power grid and the motor is large, and it is impossible to ensure that the motor starts quickly and smoothly, which affects the reliability of the motor starting. The purpose is to achieve the effect of reducing the impact on the power grid and the motor when the motor starts by switching the motor windings in series and parallel, so that the motor starts more quickly and smoothly, improving the reliability of the motor starting and widening the operating range of the motor.

[0005] The present invention provides a switching device for a motor, wherein the motor has a first set of windings and a second set of windings, and both the first set of windings and the second set of windings are three-phase windings; the switching device for the motor comprises: a first switch group and a second switch group; the first switch group is a three-way selection switch, and the three-way selection switch has a first end, a second end and a selection end; the second switch group is a two-way switch; wherein the first end of the three-phase winding of the first set of windings is connected to the midpoint of the upper and lower bridge arms in a three-phase full-bridge inverter; the first end of the first switch group is connected to the second end of the three-phase winding of the first set of windings; the second end of the first switch group is connected to the first end of the three-phase winding of the first set of windings ; The selection end of the first switch group is connected to the first end of the three-phase winding of the second set of windings; the second ends of the three-phase windings of the second set of windings are connected to form a center point; the second switch group is connected between the second ends of two adjacent phase windings of the three-phase windings of the first set of windings; wherein, when the on-off condition of the first switch group and the second switch group is the first set on-off mode, the connection mode between the first set of windings and the second set of windings is the first set connection mode; when the on-off condition of the first switch group and the second switch group is the second set on-off mode, the connection mode between the first set of windings and the second set of windings is the second set connection mode.

[0006] In some embodiments, the three-phase full-bridge inverter has a first bridge arm, a second bridge arm and a third bridge arm; the first bridge arm, the second bridge arm and the third bridge arm are sequentially arranged between the bus voltage end of the DC power supply and the output end of the three-phase full-bridge inverter; wherein the three-phase windings of the first set of windings include: U1 phase winding, V1 phase winding and W1 phase winding; the first end of the U1 phase winding of the three-phase windings of the first set of windings is connected to the midpoint of the upper and lower bridge arms in the first bridge arm, the first end of the V1 phase winding of the three-phase windings of the first set of windings is connected to the midpoint of the upper and lower bridge arms in the second bridge arm, and the first end of the W1 phase winding of the three-phase windings of the first set of windings is connected to the midpoint of the upper and lower bridge arms in the third bridge arm.

[0007] In some embodiments, the first switch group includes: a first switch, a second switch and a third switch; the second switch group includes: a fourth switch and a fifth switch; wherein the three-phase winding of the second set of windings includes: a U2 phase winding, a V2 phase winding and a W2 phase winding, and the second end of the U2 phase winding, the second end of the V2 phase winding and the second end of the W2 phase winding are connected to form a center point; the first end of the first switch is connected to the second end of the U1 phase winding in the three-phase winding of the first set of windings; the second end of the first switch is connected to the second end of the U1 phase winding in the three-phase winding of the first set of windings; connected to the first end of the U1 phase winding in the three-phase winding of the first set of windings; the selection end of the first switch is connected to the first end of the U2 phase winding in the three-phase winding of the second set of windings; the first end of the second switch is connected to the second end of the V1 phase winding in the three-phase winding of the first set of windings; the second end of the second switch is connected to the second end of the V1 phase winding in the three-phase winding of the first set of windings; the selection end of the first switch is connected to the first end of the U2 phase winding in the three-phase winding of the second set of windings; the first end of the second switch is connected to the second end of the V1 phase winding in the three-phase winding of the first set of windings; the second end of the second switch is connected to the second end of the V1 phase winding in the three-phase winding of the first set of windings; The first end of the V1 phase winding in the three-phase winding is connected to the first end of the V2 phase winding in the three-phase winding of the second set of windings; the first end of the third switch is connected to the second end of the W1 phase winding in the three-phase winding of the first set of windings; the second end of the third switch is connected to the second end of the W1 phase winding in the three-phase winding of the first set of windings; and the first end of the W1 phase winding in the three-phase winding of the first set of windings; the selection end of the third switch is connected to the V2 phase winding in the three-phase winding of the second set of windings. The first end of the W2 phase winding is connected; the second end of the U2 phase winding, the second end of the V2 phase winding, and the second end of the W2 phase winding in the three-phase winding of the second set of windings are connected to form a center point; the fourth switch is connected between the second end of the U1 phase winding in the three-phase winding of the first set of windings and the second end of the V1 phase winding in the three-phase winding of the first set of windings; the fifth switch is connected between the second end of the V1 phase winding in the three-phase winding of the first set of windings and the second end of the W1 phase winding in the three-phase winding of the first set of windings.

[0008] In some embodiments, in the first switch group, the first switch, the second switch and the third switch are all relays with single-pole double-throw switches; in the second switch group, the fourth switch and the fifth switch are all relays with single-pole single-throw switches; wherein the upper contact of the relay with the single-pole double-throw switch serves as the first end of the first switch group; the lower contact of the relay with the single-pole double-throw switch serves as the second end of the first switch group; and the contact plate of the relay with the single-pole double-throw switch serves as the selection end of the first switch group.

[0009] In some embodiments, the first setting on-off mode includes: the selection end of the first switch group is connected to the first end, and the second switch group is disconnected; the first setting connection mode includes: a series connection mode between the first set of windings and the second set of windings; the second setting on-off mode includes: the selection end of the first switch group is connected to the second end, and the second switch group is turned on; the second setting connection mode includes: a parallel connection mode between the first set of windings and the second set of windings.

[0010] Matching the above-mentioned device, the present invention further provides a compressor on the other hand, including: the switching device of the motor mentioned above.

[0011] Matching the above-mentioned device, the present invention provides an air conditioner on another aspect, including: the above-mentioned compressor, or the above-mentioned motor switching device.

[0012] Matching the above-mentioned device, the present invention provides a control method for a switching device of a motor on another aspect, comprising: when the actual connection mode between the first set of windings and the second set of windings of the motor is any one of the first set connection mode and the second set connection mode, during the operation of the motor, obtaining the actual operation status of the motor; determining whether the actual operation status of the motor has reached a preset winding switching condition; if it is determined that the actual operation status of the motor has reached the preset winding switching condition, controlling the on and off modes of the first switch group and the second switch group to switch the actual connection mode between the first set of windings and the second set of windings of the motor to the other of the first set connection mode and the second set connection mode.

[0013] In some embodiments, the actual operating condition of the motor includes: at least one actual operating parameter of the motor's target operating frequency, target speed, target voltage, and target temperature; determining whether the actual operating condition of the motor has reached a preset winding switching condition, including: determining whether the actual operating parameter of the motor is less than the preset operating parameter, so as to determine whether the actual operating condition of the motor has reached the preset winding switching condition; if it is determined that the actual operating parameter of the motor is less than the preset operating parameter, then determining that the actual operating condition of the motor has reached the winding switching condition so that the actual connection mode between the first set of windings and the second set of windings of the motor is switched from the second set connection mode to the first set connection mode; if it is determined that the actual operating parameter of the motor is greater than or equal to the preset operating parameter, then determining that the actual operating condition of the motor has reached the winding switching condition so that the actual connection mode between the first set of windings and the second set of windings of the motor is switched from the first set connection mode to the second set connection mode.

[0014] In some embodiments, controlling the on-off mode of the first switch group and the second switch group to switch the actual connection mode between the first set of windings and the second set of windings of the motor to the other connection mode of the first set of windings and the second set of windings includes: determining whether the actual connection mode between the first set of windings and the second set of windings of the motor is the first set of connection mode or the second set of connection mode; if it is determined that the actual connection mode between the first set of windings and the second set of windings of the motor is the first set of connection mode, then, upon determining that the actual operation of the motor has reached the point where the actual connection mode between the first set of windings and the second set of windings of the motor is switched from the first set of connection mode to the second set of connection mode, When the winding switching condition of the second set connection mode is met, the selection end of the first switch group is controlled to be connected to the second end, and the second switch group is turned on, so that the first set of windings and the second set of windings are connected in parallel; if it is determined that the actual connection mode between the first set of windings and the second set of windings of the motor is the second set connection mode, then when it is determined that the actual operation of the motor has reached the winding switching condition for switching the actual connection mode between the first set of windings and the second set of windings of the motor from the second set connection mode to the first set connection mode, the selection end of the first switch group is controlled to be connected to the first end, and the second switch group is turned off, so that the first set of windings and the second set of windings are connected in series.

[0015] Therefore, the scheme of the present invention forms a switching device of the motor by using five relays (i.e., a first relay, a second relay, a third relay, a fourth relay and a fifth relay) for a motor with two sets of windings (i.e., a first set of windings and a second set of windings), wherein the first relay, the second relay and the third relay are all single-pole double-throw switches, and the fourth relay and the fifth relay are all single-pole single-throw switches; in the switching device of the motor, the upper contacts of the corresponding relays in the first relay, the second relay and the third relay are respectively connected to the second ends of the corresponding windings in the three-phase windings of the first set of windings, the upper contacts of the corresponding relays in the first relay, the second relay and the third relay are respectively connected to the first ends of the corresponding windings in the three-phase windings of the first set of windings, and the first relay The contact plates of the corresponding relays in the electrical appliance, the second relay and the third relay are respectively connected to the first ends of the corresponding windings in the three-phase windings of the second set of windings, and the second ends of the corresponding windings in the three-phase windings of the second set of windings are connected together; the fourth relay and the fifth relay are respectively connected between the second ends of the adjacent two-phase windings in the three-phase windings of the first set of windings; during the operation of the motor, if the winding switching condition is met, the connection mode of the first relay, the second relay and the third relay, as well as the on and off of the fourth relay and the fifth relay are controlled to realize the series-parallel switching of the windings; thus, by switching the motor windings in series and parallel, the impact on the power grid and the motor when the motor is started is reduced, the motor is started more quickly and smoothly, the reliability of the motor starting is improved, and the motor operation range is widened.

[0016] Other features and advantages of the present invention will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the present invention.

[0017] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a structural schematic diagram of an embodiment of a switching device for a motor of the present invention;

[0019] Figure 2 It is a structural schematic diagram of an embodiment of a series-parallel winding switching control device for a motor;

[0020] Figure 3 A flow chart of an embodiment of a method for controlling series-parallel winding switching of a motor;

[0021] Figure 4 A schematic flow chart of an embodiment of a method for controlling a switching device of a motor of the present invention;

[0022] Figure 5A flow chart of an embodiment of the method of the present invention for determining whether the actual operation of the motor has reached a preset winding switching condition;

[0023] Figure 6 The present invention is a flowchart of an embodiment of controlling the on-off mode of the first switch group and the second switch group in the method of the present invention. DETAILED DESCRIPTION

[0024] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the specific embodiments of the present invention and the corresponding drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0025] Considering that in the relevant schemes, the impact on the power grid and the motor when the motor is started under heavy load is large, it is impossible to ensure that the motor starts quickly and smoothly, which affects the reliability of the motor starting. The series-parallel conversion of the motor windings can meet the needs of high-speed and efficient development. The motor windings are connected in series at low frequencies, and the current in the windings passes through each coil in turn, the total resistance increases, the total inductance increases, and it has the ability to start under heavy load and output large torque at low speed, which is suitable for high voltage and low current working scenarios; the motor windings are connected in parallel at high frequencies, and the current in the windings is distributed to each parallel branch, the total resistance is reduced, the total inductance is reduced, and it has the ability to operate at high speed and light load, which is suitable for low voltage and high current working scenarios.

[0026] In addition, in the related solutions, the motor does not have the advantages of low-speed high torque and wide speed range operation.

[0027] Therefore, the scheme of the present invention proposes a motor switching device, specifically a motor winding series-parallel switching device, which adopts a control scheme of series-parallel switching of the motor windings, can limit the starting current of the motor, reduce the impact on the power grid and the motor when the motor starts, make the motor start more quickly and smoothly, and improve the reliability of motor starting.

[0028] According to an embodiment of the present invention, a switching device for a motor is provided. Figure 1 The schematic diagram of the structure of an embodiment of the device of the present invention is shown. The motor has a first set of windings and a second set of windings, and the first set of windings and the second set of windings are both three-phase windings; the switching device of the motor includes: a first switch group and a second switch group; the first switch group is a three-way selection switch, and the three-way selection switch has a first end, a second end and a selection end; the second switch group is a two-way switch, and the two-way switch has a connection end and a selection end.

[0029] Among them, the first set of windings and the second set of windings are both arranged at the output end of the three-phase full-bridge inverter, the first end of the three-phase winding of the first set of windings is connected to the midpoint of the upper and lower bridge arms in the three-phase full-bridge inverter; the first end of the first switch group is connected to the second end of the three-phase winding of the first set of windings; the second end of the first switch group is connected to the first end of the three-phase winding of the first set of windings; the selection end of the first switch group is connected to the first end of the three-phase winding of the second set of windings; the second ends of the three-phase windings of the second set of windings are connected to form a center point; the second switch group is connected between the second ends of two adjacent phase windings in the three-phase winding of the first set of windings.

[0030] Wherein, when the on-off condition of the first switch group and the second switch group is a first set on-off mode, the connection mode between the first set of windings and the second set of windings is a first set connection mode. When the on-off condition of the first switch group and the second switch group is a second set on-off mode, the connection mode between the first set of windings and the second set of windings is a second set connection mode.

[0031] The control scheme of switching the motor windings in series and in parallel proposed in the scheme of the present invention can limit the starting current of the motor, reduce the impact on the power grid and the motor when the motor starts, make the motor start more quickly and smoothly, and can significantly improve the low-frequency energy efficiency of the high-speed motor, while further widening the motor operation range. Thus, the impact on the motor during startup can be reduced, and the motor's low-frequency load capacity and efficiency under heavy load, as well as the high-speed operation capability and energy efficiency can be further improved. That is to say, in the scheme of the present invention, by switching the winding motor in series and in parallel, the motor's low-frequency load capacity and efficiency under heavy load, as well as the high-speed operation capability and energy efficiency can be further improved, and the motor can be started smoothly and the impact on the power grid can be reduced.

[0032] In some embodiments, the three-phase full-bridge inverter has a first bridge arm, a second bridge arm and a third bridge arm; the first bridge arm, the second bridge arm and the third bridge arm are sequentially arranged between the bus voltage end of the DC power supply and the output end of the three-phase full-bridge inverter; that is, the three-phase full-bridge inverter has a first bridge arm, a second bridge arm and a third bridge arm sequentially arranged between the output end of the bus voltage Vdc and the output end of the three-phase full-bridge inverter. Wherein, the three-phase windings of the first set of windings include: U1 phase winding, V1 phase winding and W1 phase winding; the first end of the U1 phase winding of the three-phase winding of the first set of windings is connected to the midpoint of the upper and lower bridge arms in the first bridge arm, the first end of the V1 phase winding of the three-phase winding of the first set of windings is connected to the midpoint of the upper and lower bridge arms in the second bridge arm, and the first end of the W1 phase winding of the three-phase winding of the first set of windings is connected to the midpoint of the upper and lower bridge arms in the third bridge arm.

[0033] In the scheme of the present invention, a first set of windings and a second set of windings are arranged at the output end of a three-phase full-bridge inverter, and the three-phase windings of the first set of windings are connected to the midpoints of the three bridge arms of the three-phase full-bridge inverter; when the motor is running at a low speed, a larger torque is required, and at this time, the windings are switched to a series connection to increase the back electromotive force of the motor, reduce the current, and increase the torque; when the motor needs to run at a high speed, the windings are switched to a parallel connection to reduce the back electromotive force of the motor, increase the current, and increase the speed; by switching between series and parallel, both low-frequency energy efficiency and high-frequency stable operation can be guaranteed.

[0034] In some embodiments, the first switch group includes: a first switch, a second switch and a third switch; the second switch group includes: a fourth switch and a fifth switch; the first switch, the second switch and the third switch are all three-way selection switches, and the three-way selection switch has a first end, a second end and a selection end; the fourth switch and the fifth switch are both two-way switches, and the two-way switches have a connection end and a selection end.

[0035] Among them, the three-phase winding of the second set of windings includes: a U2 phase winding, a V2 phase winding and a W2 phase winding, the second end of the U2 phase winding, the second end of the V2 phase winding and the second end of the W2 phase winding are connected to form a center point; the first end of the first switch is connected to the second end of the U1 phase winding in the three-phase winding of the first set of windings; the second end of the first switch is connected to the second end of the U1 phase winding in the three-phase winding of the first set of windings; connected to the first end of the U1 phase winding in the three-phase winding of the first set of windings; the selection end of the first switch is connected to the first end of the U2 phase winding in the three-phase winding of the second set of windings.

[0036] The first end of the second switch is connected to the second end of the V1 phase winding among the three-phase windings of the first set of windings; the second end of the second switch is connected to the second end of the V1 phase winding among the three-phase windings of the first set of windings; and connected to the first end of the V1 phase winding among the three-phase windings of the first set of windings; the selection end of the second switch is connected to the first end of the V2 phase winding among the three-phase windings of the second set of windings.

[0037] The first end of the third switch is connected to the second end of the W1 phase winding in the three-phase winding of the first set of windings; the second end of the third switch is connected to the second end of the W1 phase winding in the three-phase winding of the first set of windings; connected to the first end of the W1 phase winding in the three-phase winding of the first set of windings; the selection end of the third switch is connected to the first end of the W2 phase winding in the three-phase winding of the second set of windings; the second end of the U2 phase winding, the second end of the V2 phase winding, and the second end of the W2 phase winding in the three-phase winding of the second set of windings are connected to form a center point.

[0038] The fourth switch is connected between the second end of the U1 phase winding in the three-phase winding of the first set of windings and the second end of the V1 phase winding in the three-phase winding of the first set of windings; the fifth switch is connected between the second end of the V1 phase winding in the three-phase winding of the first set of windings and the second end of the W1 phase winding in the three-phase winding of the first set of windings.

[0039] The solution of the present invention proposes a motor drive device capable of switching the connection state of the motor winding. The solution of the present invention uses relays to realize the series-parallel switching of the motor winding. In the solution of the present invention, the series-parallel winding switching motor is a three-phase motor, which has two sets of windings, five relays, and also includes a three-phase bridge inverter; by switching the series-parallel windings of the motor, the motor has the ability to start under heavy load and output large torque at low speed, and has the ability to run at high speed and light load.

[0040] In some embodiments, in the first switch group, the first switch, the second switch, and the third switch are all relays with single-pole double-throw switches; in the second switch group, the fourth switch and the fifth switch are all relays with single-pole single-throw switches.

[0041] The upper contact of the relay with a single-pole double-throw switch serves as the first end of the first switch group; the lower contact of the relay with a single-pole double-throw switch serves as the second end of the first switch group; the contact plate of the relay with a single-pole double-throw switch serves as the selection end of the first switch group. The contact plate of the relay with a single-pole single-throw switch serves as the selection end of the second switch group; the contact of the relay with a single-pole single-throw switch serves as the connection end of the second switch group.

[0042] Figure 2 FIG. 1 is a schematic diagram of a structure of an embodiment of a series-parallel winding switching control device for a motor. Figure 2 As shown, the motor is a three-phase motor; the motor drive device has two sets of windings, namely the first set of windings and the second set of windings, wherein the three-phase windings of the first set of windings are stator windings U1, stator windings V1, and stator windings W1, and the three-phase windings of the second set of windings are stator windings U2, stator windings V2, and stator windings W2. The motor drive device also has five relays, which are specifically relays K1, relays K2, relays K3, relays K4, and relays K5, wherein relays K1, relays K2, and relays K3 are single-pole double-throw switches, and the single-pole double-throw switches have upper contacts, lower contacts, and contact plates; relays K4 and relays K5 are single-pole single-throw switches.

[0043] exist Figure 2In the example shown, the three-phase bridge inverter is composed of six switch tubes (specifically, switch tubes with freewheeling diodes). In the three bridge arms where the six switch tubes are located, the switch tubes of the upper bridge arm and the switch tubes of the lower bridge arm in each bridge arm form a group of switch tubes; the first bridge arm, the second bridge arm, and the third bridge arm of the three bridge arms are sequentially arranged between the output end of the bus voltage Vdc and the three-phase winding of the motor. The two switch tubes on the first bridge arm form the first group of switch tubes, the two switch tubes on the second bridge arm form the second group of switch tubes, and the two switch tubes on the third bridge arm form the third group of switch tubes.

[0044] exist Figure 2 In the example shown, the left end of the stator winding U1 is connected between the first two switch tubes in the three-phase bridge inverter, and the right end of the stator winding U1 is connected to the upper contact of the relay K1; the left end of the stator winding V1 is connected between the second two switch tubes in the three-phase bridge inverter, and the right end of the stator winding V1 is connected to the upper contact of the relay K2; the left end of the stator winding W1 is connected between the third two switch tubes in the three-phase bridge inverter, and the right end of the stator winding W1 is connected to the upper contact of the relay K3. The left ends of the stator winding U2, stator winding V2, and stator winding W2 are connected to the contact plates of the relay K1, relay K2, and relay K3 respectively, and the right ends of the stator winding U2, stator winding V2, and stator winding W2 are connected in parallel.

[0045] exist Figure 2 In the example shown, the lower contacts of relay K1, relay K2 and relay K3 are connected to the left ends of stator winding U1, stator winding V1 and stator winding W1 respectively; the contact plate of relay K4 is connected to the upper contact of relay K1, and the other end of relay K4 is connected to the upper contact of relay K2; the contact plate of relay K5 is connected to the other end of relay K4, and the other end of relay K5 is connected to the upper contact of relay K3.

[0046] In the solution of the present invention, the series switching circuit is designed as follows: Figure 2 As shown, in the series switching circuit, the contact plates of relays K1, K2 and K3 are connected to the upper contacts of adjacent windings in sequence, relays K4 and K5 are in the disconnected state, and the windings are connected in series. Only in this way can the windings be switched between series connection and parallel connection. When connected in series, the back electromotive force is high, which is suitable for low-frequency operation with high energy efficiency.

[0047] In the solution of the present invention, the parallel switching circuit is designed as follows: In the parallel switching circuit, Figure 2 As shown, the contact plates of relays K1, K2 and K3 are connected to the lower contacts of adjacent windings in sequence, relays K4 and K5 are in the on state, and the windings are connected in parallel. Only in this way can the windings be switched between series connection and parallel connection. When connected in parallel, the back electromotive force is low, which is suitable for high-frequency operation.

[0048] In the solution of the present invention, the motor is driven in series at low speed and in parallel at high speed. By controlling five relays, the connection state of the motor winding can be switched; Figure 2 As shown, when the switches of relays K1, K2, and K3 are placed at the upper contact and relays K4 and K5 are disconnected, the connection state becomes a series connection. When the switches of relays K1, K2, and K3 are placed at the lower contact and relays K4 and K5 are turned on, the connection state becomes a parallel connection.

[0049] In the solution of the present invention, the total resistance of the two series windings is relatively high, which solves the problem in the related solution that the motor starting current is too large, the copper loss (i.e., the loss caused by the winding resistance) is reduced, and the impact on the power grid and the motor is great, so that the motor starts more quickly and smoothly, and the energy efficiency can be significantly improved. In the solution of the present invention, the two windings are connected in parallel, which increases the total current handling capacity of the motor and reduces the total resistance, solves the problem in the related solution that the motor cannot handle a larger current, and at the same time maintains a low resistance and inductance loss, thereby widening the motor operation range, which is conducive to improving the energy efficiency of the motor running at high speed.

[0050] In some embodiments, the first set on-off mode includes: the selection end of the first switch group is connected to the first end, and the second switch group is disconnected; the first set connection mode includes: a series connection mode between the first set of windings and the second set of windings; that is, when the selection end of the first switch group is connected to the first end and the second switch group is disconnected, the first set of windings and the second set of windings are connected in series.

[0051] The second setting on-off mode includes: the selection end of the first switch group is connected to the second end, and the second switch group is turned on; the second setting connection mode includes: the first set of windings and the second set of windings are connected in parallel. That is, when the selection end of the first switch group is connected to the second end and the second switch group is turned on, the connection mode between the first set of windings and the second set of windings is parallel.

[0052] When the motor runs at low speed, the motor controller sends a switching signal to the three-phase bridge inverter and sends a signal to the winding switching device at the same time, so that relays K1, K2, and K3 are closed upward, and relays K4 and K5 are disconnected. The winding connection mode is now a series connection; when the motor runs to high speed, the motor controller sends a switching signal to the three-phase bridge inverter and sends a signal to the winding switching device at the same time, so that relays K1, K2, and K3 are closed downward, and relays K4 and K5 are turned on. The winding connection mode is now a parallel connection, so that the winding can be switched between series and parallel. In series connection, the back electromotive force is high, which is suitable for low-frequency operation with high energy efficiency; in parallel connection, the back electromotive force is low, which is suitable for high-frequency operation. By switching between series and parallel, both low-frequency energy efficiency and high-frequency stable operation can be guaranteed.

[0053] In the scheme of the present invention, in order to meet the wide-speed operation requirements of the motor and take into account the higher full-band energy efficiency, a series-parallel conversion control scheme of the motor is adopted. By switching the connection method of the two sets of windings of the motor, when the motor is running at a low frequency, a winding connection method with increased total resistance and reduced total inductance (such as series winding connection) is adopted to improve the low-frequency load capacity and operating efficiency; when the motor is running at a high frequency, a winding connection method with reduced total resistance and reduced total inductance (such as parallel winding connection) is adopted to expand the operating range of the motor.

[0054] According to the technical solution of the present invention, a switching device of the motor is formed by using five relays (i.e., a first relay, a second relay, a third relay, a fourth relay, and a fifth relay) for a motor having two sets of windings (i.e., a first set of windings and a second set of windings), wherein the first relay, the second relay, and the third relay are all single-pole double-throw switches, and the fourth relay and the fifth relay are all single-pole single-throw switches; in the switching device of the motor, the upper contacts of the corresponding relays in the first relay, the second relay, and the third relay are respectively connected to the second ends of the corresponding windings in the three-phase windings of the first set of windings, the upper contacts of the corresponding relays in the first relay, the second relay, and the third relay are respectively connected to the first ends of the corresponding windings in the three-phase windings of the first set of windings, and the first relay The contact plates of the corresponding relays in the electrical appliance, the second relay and the third relay are respectively connected to the first ends of the corresponding windings in the three-phase windings of the second set of windings, and the second ends of the corresponding windings in the three-phase windings of the second set of windings are connected together; the fourth relay and the fifth relay are respectively connected between the second ends of the adjacent two-phase windings in the three-phase windings of the first set of windings; during the operation of the motor, if the winding switching condition is met, the connection mode of the first relay, the second relay and the third relay, as well as the on and off of the fourth relay and the fifth relay are controlled to realize the series-parallel switching of the windings; thus, by switching the motor windings in series and parallel, the impact on the power grid and the motor when the motor is started is reduced, the motor is started more quickly and smoothly, the reliability of the motor starting is improved, and the motor operation range is widened.

[0055] According to an embodiment of the present invention, a compressor corresponding to a switching device of a motor is also provided. The air conditioner may include: the switching device of the motor described above.

[0056] Since the processing and functions implemented by the compressor of this embodiment basically correspond to the embodiments, principles and examples of the device, for the details not described in this embodiment, please refer to the relevant descriptions in the aforementioned embodiments and will not be repeated here.

[0057] According to an embodiment of the present invention, an air conditioner corresponding to a switching device of a motor is also provided. The air conditioner may include: the compressor described above, or the switching device of the motor described above.

[0058] Since the processing and functions implemented by the air conditioner of this embodiment basically correspond to the embodiments, principles and examples of the device, for the details not described in this embodiment, please refer to the relevant descriptions in the aforementioned embodiments and will not be repeated here.

[0059] According to an embodiment of the present invention, a control method for a switching device of a motor corresponding to the switching device of the motor is also provided, such as Figure 4The flowchart of an embodiment of the method of the present invention is shown in FIG. The control method of the switching device of the motor may include: steps S110 to S130.

[0060] At step S110, when the actual connection mode between the first set of windings and the second set of windings of the motor is any one of the first set connection mode and the second set connection mode, the actual operation status of the motor is obtained during the operation of the motor.

[0061] In step S120, it is determined whether the actual operation of the motor has reached a preset winding switching condition.

[0062] At step S130, if it is determined that the actual operating condition of the motor has reached the preset winding switching condition, the on-off mode of the first switch group and the second switch group is controlled to switch the actual connection mode between the first set of windings and the second set of windings of the motor to the other connection mode of the first set connection mode and the second set connection mode.

[0063] In step S130, the first switch group includes: a first switch, a second switch and a third switch; the second switch group includes: a fourth switch and a fifth switch; the first switch, the second switch and the third switch are all three-way selection switches, and the three-way selection switches have a first end, a second end and a selection end; the fourth switch and the fifth switch are both two-way switches, and the two-way switches have a connection end and a selection end. Wherein, the three-phase winding of the second set of windings includes: a U2 phase winding, a V2 phase winding and a W2 phase winding, and the second end of the U2 phase winding, the second end of the V2 phase winding and the second end of the W2 phase winding are connected to form a center point; the first end of the first switch is connected to the second end of the U1 phase winding in the three-phase winding of the first set of windings; the second end of the first switch is connected to the second end of the U1 phase winding in the three-phase winding of the first set of windings; connected to the first end of the U1 phase winding in the three-phase winding of the first set of windings; the selection end of the first switch is connected to the first end of the U2 phase winding in the three-phase winding of the second set of windings. The first end of the second switch is connected to the second end of the V1 phase winding in the three-phase winding of the first set of windings; the second end of the second switch is connected to the second end of the V1 phase winding in the three-phase winding of the first set of windings; connected to the first end of the V1 phase winding in the three-phase winding of the first set of windings; the selection end of the second switch is connected to the first end of the V2 phase winding in the three-phase winding of the second set of windings. The first end of the third switch is connected to the second end of the W1 phase winding in the three-phase winding of the first set of windings; the second end of the third switch is connected to the second end of the W1 phase winding in the three-phase winding of the first set of windings; connected to the first end of the W1 phase winding in the three-phase winding of the first set of windings; the selection end of the third switch is connected to the first end of the W2 phase winding in the three-phase winding of the second set of windings; the second end of the U2 phase winding, the second end of the V2 phase winding, and the second end of the W2 phase winding in the three-phase winding of the second set of windings are connected to form a center point. The fourth switch is connected between the second end of the U1 phase winding in the three-phase winding of the first set of windings and the second end of the V1 phase winding in the three-phase winding of the first set of windings; the fifth switch is connected between the second end of the V1 phase winding in the three-phase winding of the first set of windings and the second end of the W1 phase winding in the three-phase winding of the first set of windings.

[0064] In the solution of the present invention, the motor is stopped to switch the winding connection mode, which is to detect that the motor reaches the winding switching condition, and then switch the winding from one state to another. By switching the connection mode of the motor winding, the starting current of the motor can be limited, the impact on the power grid and the motor when the motor starts can be reduced, the motor can be started more quickly and smoothly, the low-frequency energy efficiency of the high-speed motor can be significantly improved, and the motor operation range can be further widened. Therefore, the impact on the motor at startup can be reduced, and the motor's low-frequency load capacity and efficiency under heavy load, as well as the high-speed operation capability and energy efficiency can be further improved.

[0065] In some embodiments, the actual operation of the motor includes at least one actual operation parameter of the motor's target operating frequency, target speed, target voltage, and target temperature. For the specific process of determining whether the actual operation of the motor has reached the preset winding switching condition in step S120, see the following exemplary description.

[0066] Combine the following Figure 5 The flowchart of an embodiment of the method of the present invention for determining whether the actual operating condition of the motor has reached the preset winding switching condition is shown, which further illustrates the specific process of determining whether the actual operating condition of the motor has reached the preset winding switching condition in step S120, including: step S210 to step S230.

[0067] Step S210, determining whether the actual operating parameters of the motor are less than preset operating parameters to determine whether the actual operating conditions of the motor have reached preset winding switching conditions. The preset operating parameters include: at least one parameter of switching frequency, switching speed, switching voltage and switching temperature.

[0068] Step S220, if it is determined that the actual operating parameters of the motor are less than the preset operating parameters, it is determined that the actual operating conditions of the motor have reached a winding switching condition that causes the actual connection mode between the first set of windings and the second set of windings of the motor to switch from the second set connection mode to the first set connection mode.

[0069] Step S230, if it is determined that the actual operating parameters of the motor are greater than or equal to the preset operating parameters, it is determined that the actual operating conditions of the motor have reached the winding switching conditions for switching the actual connection mode between the first set of windings and the second set of windings of the motor from the first set connection mode to the second set connection mode.

[0070] Figure 3 FIG. 1 is a flow chart of an embodiment of a method for controlling the series-parallel winding switching of a motor. Figure 3As shown, the series-parallel winding switching control method of the motor includes: step 1, the motor is driven and operated in the first winding connection mode or the current winding connection mode, and it is detected whether the winding switching conditions (including but not limited to frequency, speed, voltage, temperature, etc.) have been met: if so, execute step 2, otherwise execute step 3.

[0071] In step 1, it is detected whether the winding switching conditions have been met, specifically, it can be: determine whether at least one of the conditions such as target frequency < switching frequency, target speed < switching speed, target voltage < switching voltage, target temperature < switching temperature is met: if it is met, it is determined that the series winding switching conditions have been met; if not, it is determined that the parallel winding switching conditions have been met.

[0072] The solution of the present invention determines whether the actual operating condition of the motor has reached the preset winding switching condition, and performs winding switching when the preset winding switching condition is reached, so as to limit the starting current of the motor, reduce the impact on the power grid and the motor when the motor starts, and enable the motor to start more quickly and smoothly. It can significantly improve the low-frequency energy efficiency of the high-speed motor, and can further improve the motor's low-frequency load capacity and efficiency under heavy load, as well as the high-speed operation capability and energy efficiency.

[0073] In some embodiments, controlling the on / off mode of the first switch group and the second switch group to switch the actual connection mode between the first set of windings and the second set of windings of the motor to the other connection mode of the first set connection mode and the second set connection mode includes:

[0074] Combine the following Figure 6 The flowchart of an embodiment of controlling the on-off mode of the first switch group and the second switch group in the method of the present invention is shown, which further illustrates the specific process of controlling the on-off mode of the first switch group and the second switch group in step S130, including: step S310 to step S330.

[0075] Step S310: determining whether the actual connection mode between the first set of windings and the second set of windings of the motor is the first set connection mode or the second set connection mode.

[0076] Step S320, if it is determined that the actual connection mode between the first set of windings and the second set of windings of the motor is the first set connection mode, then when it is determined that the actual operation of the motor has reached the winding switching condition for switching the actual connection mode between the first set of windings and the second set of windings of the motor from the first set connection mode to the second set connection mode, the selection end of the first switch group is controlled to be connected to the second end, and the second switch group is turned on, so that the first set of windings and the second set of windings are connected in parallel.

[0077] Step S330, if it is determined that the actual connection mode between the first set of windings and the second set of windings of the motor is the second set of setting connection mode, then when it is determined that the actual operation of the motor has reached the winding switching condition for switching the actual connection mode between the first set of windings and the second set of windings of the motor from the second set of setting connection mode to the first set of setting connection mode, the selection end of the first switch group is controlled to be connected to the first end, and the second switch group is disconnected, so that the first set of windings and the second set of windings are connected in series.

[0078] In step S320 and step S330, the first switch is relay K1, the second switch is relay K2, the third switch is relay K3, the fourth switch is relay K4, and the fifth switch is relay K5, wherein relay K1, relay K2, and relay K3 are single-pole double-throw switches, and the single-pole double-throw switches have upper contacts, lower contacts, and contact plates; relay K4 and relay K5 are single-pole single-throw switches. The three-phase bridge inverter is composed of six switch tubes (specifically switch tubes with freewheeling diodes), and the three bridge arms where the six switch tubes are located, the switch tubes of the upper bridge arm and the switch tubes of the lower bridge arm in each bridge arm form a group of switch tubes; the first bridge arm, the second bridge arm, and the third bridge arm of the three bridge arms are sequentially arranged between the output end of the bus voltage Vdc and the three-phase winding of the motor. The two switch tubes on the first bridge arm form a first group of switch tubes, the two switch tubes on the second bridge arm form a second group of switch tubes, and the two switch tubes on the third bridge arm form a third group of switch tubes. The left end of the stator winding U1 is connected between the first two switch tubes in the three-phase bridge inverter, and the right end of the stator winding U1 is connected to the upper contact of the relay K1; the left end of the stator winding V1 is connected between the second two switch tubes in the three-phase bridge inverter, and the right end of the stator winding V1 is connected to the upper contact of the relay K2; the left end of the stator winding W1 is connected between the third two switch tubes in the three-phase bridge inverter, and the right end of the stator winding W1 is connected to the upper contact of the relay K3. The left ends of the stator winding U2, stator winding V2, and stator winding W2 are connected to the contact plates of the relay K1, relay K2, and relay K3 respectively, and the right ends of the stator winding U2, stator winding V2, and stator winding W2 are connected in parallel. The lower contacts of relay K1, relay K2 and relay K3 are connected to the left ends of stator winding U1, stator winding V1 and stator winding W1 respectively; the contact plate of relay K4 is connected to the upper contact of relay K1, and the other end of relay K4 is connected to the upper contact of relay K2; the contact plate of relay K5 is connected to the other end of relay K4, and the other end of relay K5 is connected to the upper contact of relay K3.

[0079] like Figure 3 As shown, the series-parallel winding switching control method of the motor also includes:

[0080] Step 2, control the winding switching device of the motor to switch the winding connection mode to the second connection mode of the winding, specifically: control the contact plates of relays K1, K2 and K3 to connect the upper contacts of adjacent windings in sequence, control relays K4 and K5 to be in the disconnected state, and the windings to be connected in series, so that the windings can be switched between series and parallel.

[0081] Step 3, control the winding switching device of the motor to switch the winding connection mode to the second connection mode of the winding, specifically: control the contact plates of relays K1, K2 and K3 to connect the lower contacts of adjacent windings in sequence, control relays K4 and K5 to be in the on state, and the windings to be connected in parallel, so as to realize the switching of the windings between series connection and parallel connection.

[0082] In the scheme of the present invention, when the motor is running at a low speed, a larger torque is required. At this time, the winding is switched to a series connection to increase the back electromotive force of the motor, reduce the current, and increase the torque; when the motor needs to run at a high speed, the winding is switched to a parallel connection to reduce the back electromotive force of the motor, increase the current, and increase the speed. When connected in series, the back electromotive force is high, which is suitable for low-frequency operation with high energy efficiency; when connected in parallel, the back electromotive force is low, which is suitable for high-frequency operation; by switching between series and parallel, both low-frequency energy efficiency and high-frequency stable operation can be guaranteed.

[0083] Since the processing and functions implemented by the method of this embodiment basically correspond to the embodiments, principles and examples of the aforementioned compressor and air conditioner, for the details not exhaustive in the description of this embodiment, please refer to the relevant descriptions in the aforementioned embodiments and will not be repeated here.

[0084] In summary, it is easy for those skilled in the art to understand that, under the premise of no conflict, the above-mentioned advantageous methods can be freely combined and superimposed.

[0085] The above description is only an embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent substitution, improvement, etc. made within the spirit and principle of the present invention shall be included in the scope of the claims of the present invention.

Claims

1. A switching device for a motor, characterized in that: The motor has a first set of windings and a second set of windings, and both the first set of windings and the second set of windings are three-phase windings; The switching device of the motor includes: a first switch group and a second switch group; the first switch group is a three-way selection switch, and the three-way selection switch has a first end, a second end and a selection end; the second switch group is a two-way switch; wherein, The first end of the three-phase winding of the first set of windings is connected to the midpoint of the upper and lower bridge arms in the three-phase full-bridge inverter; the first end of the first switch group is connected to the second end of the three-phase winding of the first set of windings; the second end of the first switch group is connected to the first end of the three-phase winding of the first set of windings; the selection end of the first switch group is connected to the first end of the three-phase winding of the second set of windings; the second ends of the three-phase windings of the second set of windings are connected to form a center point; the second switch group is connected between the second ends of two adjacent phase windings in the three-phase winding of the first set of windings; Wherein, when the on-off status of the first switch group and the second switch group is a first set on-off mode, the connection mode between the first set of windings and the second set of windings is a first set connection mode; When the on-off status of the first switch group and the second switch group is a second set on-off mode, the connection mode between the first set of windings and the second set of windings is a second set connection mode.

2. The switching device of the motor according to claim 1, characterized in that: The three-phase full-bridge inverter has a first bridge arm, a second bridge arm and a third bridge arm; the first bridge arm, the second bridge arm and the third bridge arm are sequentially arranged between the bus voltage end of the DC power supply and the output end of the three-phase full-bridge inverter; wherein, The three-phase windings of the first set of windings include: U1 phase winding, V1 phase winding and W1 phase winding; the first end of the U1 phase winding in the three-phase windings of the first set of windings is connected to the midpoint of the upper and lower bridge arms in the first bridge arm, the first end of the V1 phase winding in the three-phase windings of the first set of windings is connected to the midpoint of the upper and lower bridge arms in the second bridge arm, and the first end of the W1 phase winding in the three-phase windings of the first set of windings is connected to the midpoint of the upper and lower bridge arms in the third bridge arm.

3. The switching device of the motor according to claim 1 or 2, characterized in that: The first switch group includes: a first switch, a second switch and a third switch; the second switch group includes: a fourth switch and a fifth switch; wherein, The three-phase winding of the second set of windings comprises: a U2 phase winding, a V2 phase winding and a W2 phase winding, wherein the second end of the U2 phase winding, the second end of the V2 phase winding and the second end of the W2 phase winding are connected to form a center point; the first end of the first switch is connected to the second end of the U1 phase winding in the three-phase winding of the first set of windings; the second end of the first switch is connected to the second end of the U1 phase winding in the three-phase winding of the first set of windings; and is connected to the first end of the U1 phase winding in the three-phase winding of the first set of windings; the selection end of the first switch is connected to the first end of the U2 phase winding in the three-phase winding of the second set of windings; The first end of the second switch is connected to the second end of the V1 phase winding among the three-phase windings of the first set of windings; the second end of the second switch is connected to the second end of the V1 phase winding among the three-phase windings of the first set of windings; and connected to the first end of the V1 phase winding among the three-phase windings of the first set of windings; the selection end of the second switch is connected to the first end of the V2 phase winding among the three-phase windings of the second set of windings; The first end of the third switch is connected to the second end of the W1 phase winding in the three-phase winding of the first set of windings; the second end of the third switch is connected to the second end of the W1 phase winding in the three-phase winding of the first set of windings; connected to the first end of the W1 phase winding in the three-phase winding of the first set of windings; the selection end of the third switch is connected to the first end of the W2 phase winding in the three-phase winding of the second set of windings; the second end of the U2 phase winding, the second end of the V2 phase winding, and the second end of the W2 phase winding in the three-phase winding of the second set of windings are connected to form a center point; The fourth switch is connected between the second end of the U1 phase winding in the three-phase winding of the first set of windings and the second end of the V1 phase winding in the three-phase winding of the first set of windings; the fifth switch is connected between the second end of the V1 phase winding in the three-phase winding of the first set of windings and the second end of the W1 phase winding in the three-phase winding of the first set of windings.

4. The switching device of the motor according to claim 3, characterized in that: In the first switch group, the first switch, the second switch and the third switch are all relays with single-pole double-throw switches; in the second switch group, the fourth switch and the fifth switch are all relays with single-pole single-throw switches; wherein, The upper contact of the relay with a single-pole double-throw switch serves as the first end of the first switch group; the lower contact of the relay with a single-pole double-throw switch serves as the second end of the first switch group; and the contact plate of the relay with a single-pole double-throw switch serves as the selection end of the first switch group.

5. The switching device of a motor according to any one of claims 1 to 4, characterized in that: in, The first setting on-off mode includes: the selection end of the first switch group is connected to the first end, and the second switch group is disconnected; the first setting connection mode includes: the first set of windings and the second set of windings are connected in series; The second setting on-off mode includes: the selection end of the first switch group is connected to the second end, and the second switch group is turned on; the second setting connection mode includes: a parallel connection mode between the first set of windings and the second set of windings.

6. A compressor, characterized in that: include: A switching device for an electric motor as claimed in any one of claims 1 to 5.

7. An air conditioner, characterized in that: include: A switching device for a motor as claimed in any one of claims 1 to 5, or a compressor as claimed in claim 6.

8. A method for controlling a switching device of a motor according to any one of claims 1 to 5, characterized in that: include: When the actual connection mode between the first set of windings and the second set of windings of the motor is any one of the first set connection mode and the second set connection mode, during the operation of the motor, obtaining the actual operation status of the motor; Determining whether the actual operation of the motor has reached a preset winding switching condition; If it is determined that the actual operating condition of the motor has reached the preset winding switching condition, the on-off mode of the first switch group and the second switch group is controlled to switch the actual connection mode between the first set of windings and the second set of windings of the motor to the other connection mode of the first set connection mode and the second set connection mode.

9. The control method of the switching device of the motor according to claim 8, characterized in that: The actual operation condition of the motor includes: at least one actual operation parameter of the motor among a target operation frequency, a target speed, a target voltage and a target temperature; Determining whether the actual operation of the motor has reached a preset winding switching condition includes: Determining whether the actual operating parameters of the motor are less than the preset operating parameters, so as to determine whether the actual operating conditions of the motor have reached the preset winding switching conditions; If it is determined that the actual operating parameter of the motor is less than the preset operating parameter, it is determined that the actual operating condition of the motor has reached a winding switching condition for switching the actual connection mode between the first set of windings and the second set of windings of the motor from the second set connection mode to the first set connection mode; If it is determined that the actual operating parameters of the motor are greater than or equal to the preset operating parameters, it is determined that the actual operating conditions of the motor have reached the winding switching conditions for switching the actual connection mode between the first set of windings and the second set of windings of the motor from the first set connection mode to the second set connection mode.

10. The control method of the switching device of the motor according to claim 8 or 9, characterized in that: Controlling the on / off mode of the first switch group and the second switch group to switch the actual connection mode between the first set of windings and the second set of windings of the motor to the other connection mode of the first set connection mode and the second set connection mode, including: Determining whether the actual connection mode between the first set of windings and the second set of windings of the motor is the first set connection mode or the second set connection mode; If it is determined that the actual connection mode between the first set of windings and the second set of windings of the motor is the first set connection mode, then, when it is determined that the actual operation of the motor has reached a winding switching condition for switching the actual connection mode between the first set of windings and the second set of windings of the motor from the first set connection mode to the second set connection mode, the selection end of the first switch group is controlled to be connected to the second end, and the second switch group is turned on, so that the first set of windings and the second set of windings are connected in parallel; If it is determined that the actual connection mode between the first set of windings and the second set of windings of the motor is the second set of setting connection mode, then when it is determined that the actual operating condition of the motor has reached the winding switching condition for switching the actual connection mode between the first set of windings and the second set of windings of the motor from the second set of setting connection mode to the first set of setting connection mode, the selection end of the first switch group is controlled to be connected to the first end, and the second switch group is disconnected, so that the first set of windings and the second set of windings are connected in series.

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