WO2015154697A1

WO2015154697A1 - Direct current brushless motor system for drain pump, and control method and control device thereof

Info

Publication number: WO2015154697A1
Application number: PCT/CN2015/076209
Authority: WO
Inventors: 王胜; 朋兴谱
Original assignee: 常州雷利电机科技有限公司
Priority date: 2014-04-11
Filing date: 2015-04-09
Publication date: 2015-10-15
Also published as: CN104980067A; CN104980067B

Abstract

A control method and control device of a direct current brushless motor for a drain pump, and direct current brushless motor system for the drain pump, the control method of the direct current brushless motor for the drain pump comprising: detecting the current flowing through the stator winding of the direct current brushless motor; comparing the current value of the current with a first critical current value; when the current value of the current is lower than the first critical current value, determining that the drain pump is in a half-water half-air operation state, and setting the target rotation speed of the direct current brushless motor as a first predetermined rotation speed, the first predetermined rotation speed being lower than the rated rotation speed of the direct current brushless motor. The half-water half-air state of the drain pump is identified according to the current flowing through the stator winding of the direct current brushless motor, and half-water half-air noise is reduced by reducing the target rotation speed of the direct current brushless motor in the half-water half-air state.

Description

DC brushless motor system for drain pump, control method and control device thereof

Technical field

The present invention relates to the field of drainage pump technology, and more particularly to a control method and control device for a DC brushless motor for a drainage pump of a household appliance, and a DC brushless motor system for a drainage pump of a household appliance.

Background technique

At present, single-phase AC permanent magnet synchronous motors are widely used in household appliances such as dishwashers and washing machines for their high energy efficiency and excellent steady-state characteristics. However, single-phase AC permanent magnet synchronous motors have certain limitations in terms of startup and operation performance.

For example, in the application of the washing machine drain pump, in order to solve the problem that the load of the drain pump is large and the motor is easily burned, it is necessary to add a starting device, which is mainly composed of a coupling provided with a starting rib and a starting cavity provided with a starting boss. In the instant of starting the motor, it is necessary to first idling a certain angle. When the starting rib turns to contact with the starting boss, the impeller can be driven to rotate, thereby achieving the effect of no-load starting, effectively solving the problem of burning the motor due to the large starting load. . In order to reduce the noise, a shock pad may be provided on both sides of the starting rib or on both sides of the starting boss in order to reduce the noise when the starting rib is in contact with the starting boss. The structure of the motor is relatively complicated, the assembly process is cumbersome, and the increase of the starting cavity and the cushion also greatly increases the cost, and the failure of the cushion is present after multiple starts.

Secondly, the single-phase AC permanent magnet synchronous motor itself cannot achieve directional rotation and speed regulation. It is necessary to add a non-return mechanism to the rotor structure to prevent the motor from rotating in reverse, and realize the single-phase AC permanent magnet synchronous motor by adjusting the frequency of the power supply voltage. The speed regulation is that the vibration, the noise is high and the temperature rise is high during the no-load operation, and in the later stage of the drainage process, a small amount of residual water is mixed with the air, so that the drainage pump is in a semi-aqueous and semi-air state, and the motor cannot recognize this. In the state, the impeller still rotates at high speed, producing half-water and half-air noise.

With the introduction of the concept of green household appliances and the enhancement of environmental awareness, the existing drainage pumps have been unable to meet the increasing requirements for the comfort of the living environment. Therefore, there is a need for a new type of drainage pump which is simple in structure, small in volume, high in efficiency, and low in operating noise.

Summary of the invention

In order to solve the above technical problems, according to an aspect of the present invention, a drain pump is provided A control method and a control device for a DC brushless motor, and a DC brushless motor system for a drain pump, which can recognize a half-water and a half air state of a drain pump, and reduce the target rotational speed of the DC brushless motor by being in this state Reduce the half-water and half-air noise.

According to another aspect of the present invention, a method for controlling a DC brushless motor for a drain pump includes: detecting a current flowing through a stator winding of the brushless DC motor; and current value of the current is first The critical current value is compared; if the current value of the current is lower than the first critical current value, determining that the drain pump enters a semi-aqueous half-air operating state, and the target rotating speed of the DC brushless motor is Set to a first predetermined rotational speed, wherein the first predetermined rotational speed is lower than a rated rotational speed of the direct current brushless motor.

According to an embodiment of the present invention, when the DC brushless motor is in an idle operation state, a current value of a current flowing through a stator winding of the DC brushless motor is a first current value; and the DC brushless motor is The current value of the current flowing through the stator winding of the brushless DC motor is a second current value when the rated load is in operation; wherein the first critical current value is higher than the first current value and lower than The second current value.

According to an embodiment of the invention, the control method further includes comparing a current value of the current with a second critical current value, the second critical current value being lower than the first critical current value and higher than the a first current value, and the first critical current value and the second critical current value constitute a current value interval of a semi-aqueous half air operating state; a current value of the current is lower than the second critical current value In this case, the target rotational speed of the brushless DC motor is set to the rated rotational speed of the DC brushless motor.

According to an embodiment of the invention, the first predetermined rotational speed is 60-40% of the rated rotational speed of the brushless DC motor.

According to an embodiment of the invention, the first predetermined rotational speed is 80%-60% of the rated rotational speed of the DC brushless motor; and the control method further comprises: the current value of the current and the first intermediate current value Comparing, the first intermediate current value is lower than the first critical current value and higher than the second critical current value; in a case where the current value of the current is lower than the first intermediate current value, The target rotational speed of the brushless DC motor is set to a second predetermined rotational speed, the second predetermined rotational speed being lower than the first predetermined rotational speed and being 60-40% of the rated current of the DC brushless motor.

According to an embodiment of the invention, the current flowing through the stator windings of the brushless DC motor is detected by a current detecting resistor connected in series with the stator winding.

According to an embodiment of the present invention, the control method further includes: predicting the real-time prediction by using the current a position of a rotor magnetic pole of the brushless DC motor; calculating a actual rotational speed of the DC brushless motor by using a predicted position of the rotor magnetic pole; and a target rotational speed of the DC brushless motor according to an actual rotational speed of the DC brushless motor , the current given by the stator current is given.

According to still another aspect of the present invention, a control device for a DC brushless motor for a drain pump includes: a current comparison component that compares a current value of a current flowing through a stator winding of the brushless DC motor with a first The critical current value is compared, and a first comparison result is obtained; and a target rotation speed setting unit that determines that the current value of the current is lower than the first critical current value when the first comparison result indicates that the current value of the current is lower than the first critical current value The drain pump enters a semi-aqueous half-air operating state, and sets a target rotational speed of the direct current brushless motor to a first predetermined rotational speed, wherein the first predetermined rotational speed is lower than a rated rotational speed of the direct current brushless motor.

According to an embodiment of the invention, the current comparison component further compares the current value of the current with the second critical current value, and obtains a second comparison result, the second critical current value being lower than the first critical current And a value higher than the first current value, and the first critical current value and the second critical current value constitute a current value interval of a semi-aqueous half air operating state; the target rotational speed setting component is further When the comparison result indicates that the current value of the current is lower than the second critical current value, the target rotational speed of the DC brushless motor is set to the rated rotational speed of the DC brushless motor.

According to an embodiment of the invention, the first predetermined rotational speed is 80%-60% of the rated rotational speed of the DC brushless motor; and the current comparison component compares the current value of the current with the first intermediate current value. And obtaining a third comparison result, the first intermediate current value being lower than the first critical current value and higher than the second critical current value; the target rotational speed setting component further indicating the third comparison result When the current value of the current is lower than the first intermediate current value, the target rotational speed of the DC brushless motor is set to a second predetermined rotational speed, and the second predetermined rotational speed is lower than the first predetermined rotational speed. And it is 60-40% of the rated current of the DC brushless motor.

According to still another aspect of the present invention, a DC brushless motor system for a drain pump is provided, comprising: a DC brushless motor comprising: a stator assembly and a rotor assembly, the stator assembly including a stator core and being wound in a stator core slot a stator winding, the rotor assembly includes a rotor pole; and a motor control system comprising: a drive module, a current detection module, and a control module, wherein the current detection module includes a current sense resistor connected in series with the stator winding, and passes through a current detecting resistor for detecting a current flowing through a stator winding of the brushless DC motor; the control module predicting a rotor pole of the brushless DC motor in real time according to a current of the stator winding detected by the current detecting module Positioning, calculating an actual rotational speed of the rotor pole, and outputting a control pulse signal for controlling the driving module according to a target rotational speed of the DC brushless motor and an actual rotational speed of the DC brushless motor; wherein the control The module is also at the current value of the current is lower than the first critical current In the case of a value, determining that the drain pump enters a semi-aqueous half air operating state, and setting a target rotational speed of the direct current brushless motor to a first predetermined rotational speed, wherein the first predetermined rotational speed is lower than the direct current Brush the rated speed of the motor.

According to an embodiment of the invention, the number of stator core slots is the same as the number of rotor poles, and the radial air gap formed by the rotor poles and the stator core is a non-uniform air gap.

According to an embodiment of the invention, the driving module comprises an H-bridge inverter; and the control pulse signal output by the control module is a switch control pulse signal for controlling four switches in the H-bridge inverter.

According to an embodiment of the present invention, when the DC brushless motor is in an idle operation state, a current value of a current flowing through a stator winding of the DC brushless motor is a first current value; and the DC brushless motor is The current value of the current flowing through the stator winding of the brushless DC motor is a second current value when the load is in a rated load operating state; wherein the first critical current value is higher than the first current value and lower than The second current value.

According to an embodiment of the present invention, the control module further sets a target rotational speed of the DC brushless motor to the DC brushless motor, if the current value of the current is lower than the second critical current value. The rated rotational speed, the second critical current value is lower than the first critical current value, and the first critical current value and the second critical current value constitute a current value interval of the semi-aqueous half air operating state.

According to an embodiment of the invention, the first predetermined rotational speed is a rated turn of the DC brushless motor 80%-60% of the speed; the control module further sets the target rotational speed of the DC brushless motor to a second predetermined rotational speed if the current value of the current is lower than the first intermediate current value, The first intermediate current value is lower than the first critical current value and higher than the second critical current value, and the second predetermined rotational speed is lower than the first predetermined rotational speed and is a rated current of the DC brushless motor 60-40%.

A control method and a control device for a DC brushless motor for a drain pump according to an embodiment of the present invention, and a DC brushless motor system for a drain pump, by using a current value of a current flowing through a stator winding of the DC brushless motor Presetting a critical current value corresponding to a critical point of the semi-aqueous half-air state of the drain pump, determining whether the drain pump enters a semi-aqueous half-air state, and further determining that the drain pump enters a semi-aqueous half air In the case of the state, the target rotational speed of the brushless DC motor is lowered, thereby reducing the half-water and half-air noise generated by the drain pump, and at the same time enabling the drain pump to completely discharge the remaining water.

Other features and advantages of the invention will be set forth in the description which follows, The objectives and other advantages of the invention may be realized and obtained by means of the structure particularly pointed in the appended claims.

DRAWINGS

The drawings are intended to provide a further understanding of the invention, and are intended to be a In the drawing:

1 is a schematic view showing the overall structure of a DC brushless motor system for a drain pump according to an embodiment of the present invention;

2 illustrates a schematic block diagram of a motor control system in a drain pump in accordance with an embodiment of the present invention;

3 is a block diagram showing a specific structure of a motor control system according to an embodiment of the present invention;

4 illustrates a control schematic diagram implemented by control module 22 in accordance with an embodiment of the present invention;

Figure 5 is a schematic view showing the working phase of a DC brushless motor for a drain pump according to an embodiment of the present invention;

FIG. 6 illustrates a schematic flow chart of a method 600 of controlling a brushless DC motor in accordance with an embodiment of the present invention;

FIG. 7 illustrates a schematic block diagram of a control device 700 of a DC brushless motor for a drain pump according to an embodiment of the present invention.

detailed description

Various embodiments in accordance with the present invention will be described in detail with reference to the accompanying drawings. Here, it is to be noted that in the drawings, the same reference numerals are given to the components having substantially the same or similar structures and functions, and repeated description thereof will be omitted.

DC brushless motors have been widely used in various fields due to their small size, good dynamic response characteristics, large starting torque and strong overload capability. The brushless DC motor has the advantage that the single-phase AC permanent magnet synchronous motor can not be compared in terms of starting. It can provide a large starting torque in addition to the starting device. Therefore, in the present invention, a DC brushless motor is applied to the field of household appliance drainage pumps such as dishwashers and washing machines.

1 is a schematic view showing the overall structure of a DC brushless motor system for a drain pump according to an embodiment of the present invention. The DC brushless motor system for a drain pump shown in FIG. 1 includes a DC brushless motor 1 and a motor control system 2.

The brushless DC motor 1 includes a stator assembly including a stator core and stator windings wound in a stator core slot, and a rotor assembly including a rotor pole.

Specifically, the stator winding is a single-phase bipolar winding wound in a stator core slot according to a certain regularity. In the brushless DC motor 1, the radial air gap formed by the rotor pole and the stator core is a non-uniform air gap, a position where the air gap is large, a large magnetic resistance, a small air gap, and a small magnetic resistance.

With the rotation of the rotor pole, when the air gap between the rotor pole and the stator core gradually changes from large to small, that is, when the magnetic resistance of the rotor pole rotates from large to small, the running performance of the brushless DC motor 1 can be Get optimized.

The structure of the motor of the brushless DC motor is well known to those skilled in the art, and therefore, in order to avoid obscuring the present invention, the motor structure of the brushless DC motor will not be described herein.

FIG. 2 shows a detailed schematic of a motor control system 2 in accordance with an embodiment of the present invention.

As shown in FIG. 2, the motor control system 2 includes a drive module 21, a control module 22, and a current detection module 23 in accordance with an embodiment of the present invention.

The driving module 21 supplies power to the DC brushless motor, and the driving module 21 has two output terminals A and B. The output polarity is adjustable between the first output end A and the second output end B, and the width can be And a voltage pulse having a constant amplitude, the voltage pulse driving the DC brushless motor to rotate.

FIG. 3 shows a block diagram of a specific structure of a motor control system according to an embodiment of the present invention.

As shown in FIG. 3, the driving module 21 may include an H-bridge inverter circuit, and the driving mode Block 21 receives a four-way switch control signal from the control module 22, the switch control signal may be a PWM signal, and respectively controls four bridge arms of the H-bridge inverter circuit according to the received four-way switch control signal The switch in and out of the switch. In order not to obscure the present invention, the generation of the PWM signal is not specifically described herein.

According to an embodiment of the invention, each of the bridge arms of the H-bridge inverter circuit includes a controllable switch, and the controllable switch is, for example, a switching device such as a MOSFET or an IGBT.

As shown in FIG. 3, the H-bridge inverter circuit includes switches Q1, Q2, Q3, and Q4, wherein switches Q1 and Q3 are located in the upper arm, switches Q2 and Q4 are located in the lower arm, and switches Q1 and Q3 are The connection point between the two constitutes the first input terminal M, the connection point between the switch Q2 and the switch Q4 constitutes the second input terminal N, the connection point of the switch Q1 and the switch Q2 constitutes the first output terminal A, and the connection of the switch Q3 and the switch Q4 The dots constitute a second output terminal B.

The polarity and width of the voltage pulse applied between the first output terminal A and the second output terminal B can be controlled by controlling the on and off of the switches Q1, Q2, Q3 and Q4.

For example, assume that the voltage between the first input terminal M and the second input terminal N is positive, and when Q1 and Q4 are on, at the first input terminal A and the second input terminal The polarity of the voltage pulse between B is positive polarity. Conversely, when Q2 and Q3 are turned on, the polarity of the voltage pulse between the first input terminal A and the second input terminal B is negative polarity. .

Further, the drive module 21 may further include a level conversion circuit (not shown) that receives the four-way switch control signal from the control module 22 and receives the received four, as needed. The switch control signals are level-converted to obtain four-way switch drive signals for driving the switches Q1, Q2, Q3 and Q4 in the H-bridge inverter circuit, respectively. For example, the high level of the four-way switch control signal may be 5V, and the high level of the four-way switch drive signal may be 12V.

The current detecting module 23 may include a current detecting resistor connected in series with the stator winding, the current detecting resistor detecting a current flowing through a stator winding of the brushless DC motor.

As an example, the current detecting module 23 may include two current detecting resistors respectively detecting currents flowing through the switches Q2 and Q4 in the H-bridge inverter circuit, that is, in the H-bridge The current flowing through the stator windings of the brushless DC motor when the switches Q2 and Q4 in the inverter circuit are respectively turned on.

In addition, the current detecting module 23 may further include a current processing submodule, and the current processing submodule may include a current amplifying part and an AD converting part; the current amplifying part Receiving a current of the stator winding detected by the current detecting resistor, amplifying the current by a predetermined multiple, and outputting the amplified current to an AD conversion component; the AD conversion component amplifying the current amplifying component The current is A/D converted and the converted digital quantity is input to the control module 22.

The control module 22 can receive the current flowing through the stator winding of the DC brushless motor output by the current detecting module 23, and can use the current to predict the position of the rotor magnetic pole of the DC brushless motor in real time, and utilize Calculating the actual rotational speed of the DC brushless motor, and generating a current reference value of the stator current according to the target rotational speed of the DC brushless motor and the actual rotational speed of the DC brushless motor, and then outputting A control pulse signal for controlling the driving module, that is, the four-way switch control signal.

4 shows a control schematic diagram implemented by control module 22 in accordance with an embodiment of the present invention.

As shown in FIG. 4, the control module 22 can include a speed outer loop control sub-module 221 and a current inner loop control sub-module 222.

The speed outer loop control sub-module 221 implements a closed loop control function of the speed outer loop, which calculates a speed difference between the current speed of the DC brushless motor (ie, the actual speed) and the target speed, and based on the speed difference The current reference value of the current inner loop is obtained.

According to an embodiment of the present invention, the speed outer loop control sub-module 221 may include a speed PID controller, and the speed PID controller performs a PID (proportional-integral-derivative) operation on the speed difference to obtain the current. Desired point. The control performance of the DC brushless motor control system can be adjusted by adjusting the proportional coefficient, the integral coefficient, and the differential coefficient of the speed PID controller.

The current inner loop control sub-module 222 implements a closed loop control function of the current inner loop, which calculates the current stator current of the DC brushless motor (eg, the current of the stator winding detected by the current detecting module 23) a current difference between the current setpoints provided by the speed outer loop control sub-module 221, and controlling a duty cycle of the voltage pulse supplied by the drive module to the stator winding of the brushless DC motor based on the current difference .

According to an embodiment of the invention, the current loop control sub-module 222 may include a current PID controller, and the current PID controller performs a PID (proportional-integral-derivative) operation on the speed difference to obtain the current Value. The control performance of the DC brushless motor control system can be adjusted by adjusting the proportional coefficient, the integral coefficient, and the differential coefficient of the current PID controller.

According to an embodiment of the present invention, when the DC brushless motor is in an idle operation state, the target rotational speed of the DC brushless motor is its rated rotational speed, and at this time, the DC brushless electric motor flows. The current value of the current of the stator winding of the machine is a first current value; and when the DC brushless motor is in a rated load operating state, the target rotational speed of the DC brushless motor is also its rated speed, at this time, the flow The current value of the current through the stator winding of the brushless DC motor is a second current value. According to the operating principle of the DC brushless motor, the second current value is higher than the first current value.

After the drain pump discharges part of the water, when the brushless DC motor is in the semi-aqueous half-air state, the load of the brushless DC motor is lower than the rated load, if the target speed of the DC brushless motor is still The rated speed, the speed closed-loop control sub-module 221 will control the DC brushless motor to maintain its constant speed, the speed closed-loop control sub-module 221 outputs a stator current reference value, and the current closed-loop control sub-module 222 passes the adjustment The duty ratio of the voltage pulse supplied by the driving module to the stator winding of the brushless DC motor to control the current flowing through the stator winding of the brushless DC motor is equal to the stator current given value, at this time, flowing The current of the stator winding of the brushless DC motor is a third current value. According to the operating principle of the DC brushless motor, the second current value is higher than the third current value, and the third current value is higher than the first current value.

As described above, if the DC brushless motor for the drain pump enters the semi-aqueous half-air operating state, the DC brushless motor still drives the impeller to rotate at a high speed, resulting in a large half-half air noise.

According to an embodiment of the invention, the semi-aqueous half-air operating state of the brushless DC motor is identified based on a current value of a current flowing through a stator winding of the brushless DC motor, and the semi-aqueous half air is identified Reducing the target rotational speed of the DC brushless motor after the operating state, that is, reducing the target rotational speed of the DC brushless motor in the semi-aqueous half air operating state, thereby achieving the purpose of reducing the semi-aqueous half air noise, and the DC The brushless motor continues to operate at a reduced rotational speed to drive the impeller portion to discharge all of the remaining water.

Fig. 5 is a view showing the working phase of a DC brushless motor for a drain pump according to an embodiment of the present invention.

First, in the startup phase S1, the speed closed-loop control sub-module 221 and the current closed-loop control sub-module 222 are both in an open loop state, and the switches Q1 and Q4 in the H-bridge inverter circuit are turned on. The polarity of the voltage pulse outputted between the first output terminal A and the second output terminal B of the H-bridge inverter circuit is positive polarity, in other words, A→B is performed on the stator winding of the DC brushless motor. The direction is pre-energized, in which case a series of voltage pulses are output between the first output A and the second output B of the H-bridge inverter circuit. The magnetic field formed by pre-energizing the stator winding of the brushless DC motor can form a repulsive force or a suction force with the magnetic field of the rotor pole, thereby The rotating rotor pole rotates at a slight angle, so that the rotor obtains a very small speed. When the stator current signal of the complete electrical cycle is obtained, the position of the rotor pole can be determined based on the stator current signal. Then, the speed closed loop control sub-module 221 and the current closed loop control sub-module 222 enter a closed-loop operating state, and perform closed-loop control on the rotational speed of the DC brushless motor for the drain pump.

After the control module 22 is able to determine the position of the rotor pole of the DC brushless motor, the speed outer loop control sub-module 221 and the current inner loop control sub-module 222 in the control module 22 control the The brushless DC motor accelerates until the target speed (eg, rated speed) is reached.

Then, the DC brushless motor enters the stable operation phase S2 under the control of the control module 21.

After the drain pump begins to drain, there is a case where water and air are mixed, the load of the brushless DC motor is reduced, and correspondingly controlled by the speed outer loop control sub-module 221 in the control module 22 Adjusting the stator current setting value to maintain the rotation speed of the DC brushless motor is substantially constant, and adjusting the driving module to the stator winding of the DC brushless motor by the control of the current inner loop control sub-module 222 The duty cycle of the supplied voltage pulse outputs a stator current that conforms to the stator current setpoint. Specifically, the speed outer loop control sub-module 221 will reduce the output stator current set value, and the current value of the current flowing through the stator winding of the brushless DC motor is also reduced.

As the displacement of the drain pump increases, more and more air enters, at which point the drain pump enters the semi-aqueous half-air operating phase S3. In this stage, especially in the later stage of the drainage process, a small amount of water remains mixed with the air. If the brushless DC motor still rotates the impeller portion at a high speed, the drain pump will generate a larger half-water half. Air noise.

The control method of the DC brushless motor according to the embodiment of the present invention will mainly be directed to the identification of the semi-aqueous half-air stage and the subsequent processing, and the control method of the DC brushless motor according to the embodiment of the present invention will be specifically described below with reference to FIG. .

Then, when the drain pump drains water, the drain pump enters the water emptying stage S4, and accordingly the DC brushless motor becomes idling.

Next, depending on actual needs, there may be a water recovery phase S5, or there may be no water recovery phase S5.

FIG. 6 illustrates a schematic flow diagram of a method 600 of controlling a brushless DC motor in accordance with an embodiment of the present invention.

At step S610, a current flowing through the stator winding of the brushless DC motor is detected.

In step S620, the current value of the current is compared with the first critical current value.

In the case where the current value of the current is lower than the first critical current value, the control method of the DC brushless motor according to the embodiment of the present invention proceeds to step S630.

At step S630, it is determined that the drain pump enters a semi-aqueous half air operating state, and sets a target rotational speed of the direct current brushless motor to a first predetermined rotational speed, wherein the first predetermined rotational speed is lower than the direct current brushless The rated speed of the motor. According to an embodiment of the invention, after the drain pump begins to drain, there is a case where there is a mixture of water and air, the load of the brushless DC motor is reduced, correspondingly through the speed outer ring in the control module 22 Controlling the sub-module 221 and the current inner loop control sub-module 222 to adjust (specifically, reduce) the duty cycle of the voltage pulse supplied by the driving module to the stator winding of the brushless DC motor, thereby adjusting Specifically (reducing) the current flowing through the stator windings of the brushless DC motor, such that the actual rotational speed of the brushless DC motor is substantially consistent with the target rotational speed.

As described above, since the load of the brushless DC motor becomes smaller as the displacement of the drain pump increases, the current flowing through the stator winding of the brushless DC motor also decreases.

The control module 22 may determine that the current value of the current flowing through the stator winding of the brushless DC motor gradually decreases to the first critical current value by setting a predetermined first critical current value. The DC brushless motor enters a semi-water and semi-air state, at which time the target rotational speed of the drain brush DC brushless motor can be reduced, thereby reducing the half-water and half-air noise of the drain pump. The first critical current value here is only a set value, in fact, as long as the drain pump starts to drain, the DC brushless motor enters a state of water and air mixing, but at this time the proportion of air is small and the drainage The noise generated by the pump is within the allowable range. For example, the predetermined first critical current value may be selected according to the noise generated by the drain pump, or may be selected according to the proportion of air.

As described above, when the DC brushless motor is in an idle operation state, a current value of a current flowing through a stator winding of the DC brushless motor is a first current value; and the DC brushless motor is at The current value of the current flowing through the stator winding of the brushless DC motor is a second current value when the rated load is in operation; wherein the second current value is higher than the first current value. As an example, the first critical current value may be selected as a value between the first current value and the second current value, for example, 80%-70% of the second current value, ie, The first critical current value is higher than the first current value and lower than the second current value.

The current value of the current flowing through the stator winding of the brushless DC motor is between the first When the boundary current value and the second current value are between, it is considered that the DC brushless motor does not enter the semi-aqueous half air state, and the target rotational speed of the DC brushless motor remains unchanged.

When the current value of the current flowing through the stator winding of the brushless DC motor is reduced to be equal to or lower than the first critical current value, determining that the drain brush DC brushless motor enters a semi-aqueous half-air state, and At this time, the target rotational speed of the drain brush DC brushless motor is lowered, for example, the target rotational speed at this time is set to the first predetermined rotational speed, and the first predetermined rotational speed may be, for example, 40% to 60 of the rated rotational speed. %.

In the control method of the brushless DC motor according to the embodiment of the present invention, a predetermined second critical current value may be further set, the second critical current value being lower than the first critical current value, and the first The critical current value and the second critical current value constitute a current value interval of the semi-aqueous half air operating state. When the current flowing through the stator winding of the brushless DC motor is lower than the second critical current value, it is basically considered that the drain pump drain is completed, and the original target rotational speed of the DC brushless motor can be restored. At this time, the drain pump can enter the water emptying stage S4. Specifically, the control method of the DC brushless motor according to the embodiment of the present invention may further include: comparing a current value of the current with a second critical current value, wherein a current value of the current is lower than the second critical In the case of the current value, the target rotational speed of the brushless DC motor is set to the rated rotational speed of the DC brushless motor.

Alternatively, according to an embodiment of the present invention, it is also possible to reduce the target rotational speed of the drain pump DC brushless motor step by step. For example, in addition to the first predetermined rotational speed, a second predetermined rotational speed, or even a third predetermined rotational speed, may be provided.

As an example, in the case of setting the first predetermined rotational speed and the second predetermined rotational speed, the first predetermined rotational speed may be 80%-60% of the rated rotational speed of the DC brushless motor, the second predetermined The rotation speed may be 60-40% of the rated rotation speed of the DC brushless motor; in this case, the control method may further include: comparing the current value of the current with the first intermediate current value, the An intermediate current value is lower than the first critical current value and higher than the second critical current value; and when the current value of the current is lower than the first intermediate current value, the DC brushless is used The target speed of the motor is set to a second predetermined speed.

As another example, in a case where the first predetermined rotational speed, the second predetermined rotational speed, and the third predetermined rotational speed are set, the first predetermined rotational speed may be 85%-70 of the rated rotational speed of the DC brushless motor. %, the second predetermined rotational speed may be 70%-55% of the rated rotational speed of the DC brushless motor, and the third predetermined rotational speed may be 55% of the rated rotational speed of the DC brushless motor- 40%; in this case, the control method may further include: comparing a current value of the current with a first intermediate current value, the first intermediate current value being lower than the first critical current value and high And setting, at the second critical current value, a target rotational speed of the DC brushless motor to a second predetermined rotational speed, where the current value of the current is lower than the first intermediate current value; The current value is compared with a second intermediate current value that is lower than the first intermediate current value and higher than the second critical current value, the current value at the current being lower than the In the case of the second intermediate current value, the target rotational speed of the brushless DC motor is set to a third predetermined rotational speed.

Thus, by reducing the target rotational speed of the drain brush DC brushless motor after entering the semi-aqueous half-air state, the semi-aqueous half-air noise generated by the drain pump in the semi-aqueous half-air state in the late stage of drainage can be reduced, and The remaining water can still be completely drained.

In order to ensure that the target current speed is not lowered even if the current value of the stator current is less than the first critical current value in the initial stage of the current rising process of the startup phase S1, the current value and the current value of the stator current may be The target speed is decreased when both are less than the first critical current value. Correspondingly, in the case where the first intermediate current value is present, the target speed can be lowered when both the current set value and the current value of the stator current are less than the first intermediate current value.

Additionally, a current filter can be included in the current inner loop control sub-module 222, which can produce a predetermined delay. Thus, during the start-up phase S1 current rise, due to the delay of the current filter, the current value of the stator current compared with the current reference value in the start-up phase S1 is not lower than the first The critical current value, correspondingly, does not fall within the current value range of the semi-aqueous half-air operating state.

In addition, alternatively, after the actual rotational speed of the brushless DC motor reaches a predetermined percentage (eg, 90%) of the target rotational speed, or the current value of the stator current may be higher than the first critical current value for the first time Thereafter, the current value of the stator current is compared with the first critical current value.

Fig. 7 shows a schematic block diagram of a control device 700 for a DC brushless motor for a drain pump according to an embodiment of the present invention.

As shown in FIG. 7, a control device 700 for a DC brushless motor for a drain pump according to an embodiment of the present invention may include a current comparison unit 710 and a target rotation speed setting unit 720.

The current comparison part 710 compares the current value of the current flowing through the stator winding of the brushless DC motor with the first critical current value, and obtains a first comparison result.

The target rotation speed setting part 720 indicates that the current value of the current is lower than the first comparison result In the case of the first critical current value, determining that the drain pump enters a semi-aqueous half-air operating state, and setting a target rotational speed of the direct current brushless motor to a first predetermined rotational speed, wherein the first predetermined rotational speed It is lower than the rated speed of the DC brushless motor.

According to an embodiment of the present invention, when the DC brushless motor is in an idle operation state, a current value of a current flowing through a stator winding of the DC brushless motor is a first current value; and the DC brushless motor is The current value of the current flowing through the stator winding of the brushless DC motor is a second current value when the load is in a rated load operating state; wherein the first critical current value is higher than the first current value and is low And the second current value.

According to an embodiment of the present invention, in addition to setting a predetermined first critical current value, a predetermined second critical current value may be set, the second critical current value being lower than the first critical current value, and The first critical current value and the second critical current value constitute a current value interval of the semi-aqueous half air operating state. When the current flowing through the stator winding of the brushless DC motor is lower than the second critical current value, it is basically considered that the drain pump drain is completed, and the original target rotational speed of the DC brushless motor can be restored. Specifically, according to the embodiment of the present invention, the current comparison component 710 compares the current value of the current with the second critical current value to obtain a second comparison result, where the second comparison result indicates the current value of the current. Below the second critical current value, the target rotational speed setting component 720 sets the target rotational speed of the DC brushless motor to the rated rotational speed of the DC brushless motor.

Further, according to an embodiment of the present invention, as an example, the first predetermined rotational speed may be, for example, 40% to 60% of the rated rotational speed.

Alternatively, according to an embodiment of the present invention, it is also possible to reduce the target rotational speed of the drain pump DC brushless motor step by step. For example, in addition to the first predetermined rotational speed, a second predetermined rotational speed, or even a third predetermined rotational speed, may be set.

As an example, in the case of setting the first predetermined rotational speed and the second predetermined rotational speed, the first predetermined rotational speed may be 80%-60% of the rated rotational speed of the DC brushless motor, the second predetermined The speed may be 60-40% of the rated speed of the brushless DC motor; in this case, the current comparison component 710 compares the current value of the current with the first intermediate current value to obtain a third comparison. As a result, the first intermediate current value is lower than the first critical current value and higher than the second critical current value; and the third comparison result indicates that the current value of the current is lower than the first intermediate In the case of the current value, the target rotational speed setting part 720 sets the target rotational speed of the direct current brushless motor to the second predetermined rotational speed.

As another example, in a case where the first predetermined rotational speed, the second predetermined rotational speed, and the third predetermined rotational speed are set, the first predetermined rotational speed may be 85%-70 of the rated rotational speed of the DC brushless motor. %, the second predetermined rotational speed may be 70%-55% of the rated rotational speed of the DC brushless motor, and the third predetermined rotational speed may be 55%-40% of the rated rotational speed of the DC brushless motor; In this case, the current comparison component 710 also compares the current value of the current with a first intermediate current value that is lower than the first critical current value and higher than the first a second critical current value, in a case where the current value of the current is lower than the first intermediate current value, the target rotational speed setting unit 720 sets a target rotational speed of the DC brushless motor to a second predetermined rotational speed; The current comparison component 710 also compares the current value of the current with a second intermediate current value that is lower than the first intermediate current value and higher than the second critical current value. The current The current value is lower than a second intermediate current value of the target rotational speed setting means 720 to the DC brushless motor target rotation speed is set to a third predetermined rotational speed.

Thus, by reducing the target rotational speed of the drain brush DC brushless motor after entering the semi-aqueous half-air state, the semi-aqueous half-air noise generated by the drain pump in the semi-aqueous half-air state in the late stage of drainage can be reduced, and The remaining water can still be completely drained. Further, the control device 700 for a DC brushless motor for a drain pump according to an embodiment of the present invention may further include: a rotor position predicting section, a speed calculating section, and a given current calculating section (not shown).

The rotor position predicting means predicts the position of the rotor of the brushless DC motor in real time using the detected current flowing through the stator windings of the brushless DC motor.

The speed calculation component calculates the current actual rotational speed of the brushless DC motor using the predicted rotor position.

The given current calculation unit generates a current reference value of the stator current using the current actual rotational speed of the DC brushless motor and the target rotational speed of the DC brushless motor.

A control method and a control device for a DC brushless motor for a drain pump and a DC brushless motor system for a drain pump according to an embodiment of the present invention have been described with reference to FIGS. 1 to 7 by flowing a DC brushless motor Comparing the current value of the current of the stator winding with a preset critical current corresponding to the critical point of the semi-aqueous half-air state of the drain pump, determining whether the drain pump enters a semi-aqueous half-air state, and further Reducing the target rotational speed of the DC brushless motor in the case where the drain pump enters the semi-aqueous half-air state, thereby reducing the half-water and half-air noise generated by the drain pump, and at the same time enabling the drain pump to retain the remaining water Completely discharged.

Various embodiments of the present invention have been described in detail above. However, those skilled in the art should The various modifications, combinations or sub-combinations of these embodiments may be made without departing from the spirit and scope of the invention, and such modifications are intended to fall within the scope of the invention.

This application claims priority from China Priority Application filed on April 11, 2014, with the application number "CN 201410146700.1" and the name of the invention as "DC brushless motor system for drain pump, and its control method and control device". The entire content is incorporated herein.

Claims

A control method for a DC brushless motor for a drainage pump, comprising:

Detecting a current flowing through a stator winding of the brushless DC motor;

Comparing the current value of the current with a first critical current value;

When the current value of the current is lower than the first critical current value, determining that the drain pump enters a semi-aqueous half air operating state, and setting a target rotational speed of the direct current brushless motor to a first predetermined rotational speed Wherein the first predetermined rotational speed is lower than a rated rotational speed of the brushless DC motor.
The control method according to claim 1, wherein

When the DC brushless motor is in an idle operation state, a current value of a current flowing through a stator winding of the DC brushless motor is a first current value;

When the brushless DC motor is in a rated load operating state, a current value of a current flowing through a stator winding of the brushless DC motor is a second current value;

Wherein the first critical current value is higher than the first current value and lower than the second current value.
The control method of claim 2, further comprising:

Comparing a current value of the current with a second critical current value, the second critical current value being lower than the first critical current value and higher than the first current value, and the first critical current value And the second critical current value constitutes a current value interval of the semi-aqueous half air operating state;

In a case where the current value of the current is lower than the second critical current value, the target rotational speed of the DC brushless motor is set to a rated rotational speed of the DC brushless motor.
The control method according to claim 1, wherein

The first predetermined rotational speed is 60-40% of the rated rotational speed of the brushless DC motor.
The control method according to claim 3, wherein said first predetermined rotational speed is 80% - 60% of a rated rotational speed of said brushless DC motor; and said control method further comprises:

Comparing a current value of the current with a first intermediate current value, the first intermediate current value being lower than the first critical current value and higher than the second critical current value;

Setting a target rotational speed of the brushless DC motor to a second predetermined rotational speed, wherein the second predetermined rotational speed is lower than the first predetermined condition, in a case where a current value of the current is lower than the first intermediate current value The rotational speed is 60-40% of the rated rotational speed of the brushless DC motor.
The control method according to claim 1, wherein

A current flowing through a stator winding of the brushless DC motor is detected by a current detecting resistor connected in series with the stator winding.
The control method of claim 1 further comprising:

Using the current to predict the position of the rotor pole of the brushless DC motor in real time;

Calculating the actual rotational speed of the brushless DC motor using the predicted position of the rotor pole;

A current reference value of the stator current is generated according to the actual rotational speed of the DC brushless motor and the target rotational speed of the DC brushless motor.
A control device for a DC brushless motor for a drain pump, comprising:

a current comparison component that compares a current value of a current flowing through a stator winding of the brushless DC motor with a first critical current value, and obtains a first comparison result;

a target rotation speed setting unit that determines that the drain pump enters a semi-aqueous half air operation state in a case where the first comparison result indicates that a current value of the current is lower than the first critical current value, and the The target rotational speed of the brushless DC motor is set to a first predetermined rotational speed, wherein the first predetermined rotational speed is lower than the rated rotational speed of the DC brushless motor.
The control device according to claim 8, wherein

When the DC brushless motor is in an idle operation state, a current value of a current flowing through a stator winding of the DC brushless motor is a first current value;

When the brushless DC motor is in a rated load operating state, a current value of a current flowing through a stator winding of the brushless DC motor is a second current value;

Wherein the first critical current value is higher than the first current value and lower than the second current value.
The control device according to claim 9, wherein

The current comparison component further compares the current value of the current with a second critical current value, and obtains a second comparison result, the second critical current value being lower than the first critical current value and higher than the a first current value, and the first critical current value and the second critical current value constitute a current value interval of a semi-aqueous half air operating state;

The target rotation speed setting unit further sets the target rotation speed of the DC brushless motor to the DC current if the second comparison result indicates that the current value of the current is lower than the second critical current value. Brush the rated speed of the motor.
The control device according to claim 8, wherein

The first predetermined rotational speed is 60-40% of the rated rotational speed of the brushless DC motor.
The control device according to claim 10, wherein said first predetermined rotational speed is 80% - 60% of a rated rotational speed of said brushless DC motor;

The current comparison component further compares the current value of the current with the first intermediate current value, and obtains a third comparison result, the first intermediate current value being lower than the first critical current value and higher than the Second critical current value;

The target rotation speed setting unit further sets the target rotation speed of the DC brushless motor to a second predetermined rotation speed, in a case where the third comparison result indicates that the current value of the current is lower than the first intermediate current value. The second predetermined rotational speed is lower than the first predetermined rotational speed and is 60-40% of the rated current of the brushless DC motor.
A DC brushless motor system for a drain pump, comprising:

A brushless DC motor comprising: a stator assembly and a rotor assembly, the stator assembly including a stator core and stator windings wound in the stator core slots, the rotor assembly including rotor poles;

A motor control system comprising: a drive module, a current detection module, and a control module,

Wherein the current detecting module includes a current detecting resistor connected in series with the stator winding, and detecting a current flowing through a stator winding of the brushless DC motor through the current detecting resistor;

The control module predicts the position of the rotor magnetic pole of the DC brushless motor in real time according to the current of the stator winding detected by the current detecting module, calculates the actual rotational speed of the rotor magnetic pole, and according to the DC brushless motor a target rotational speed and an actual rotational speed output of the DC brushless motor for controlling a control pulse signal of the driving module;

Wherein, the control module further determines that the drain pump enters a semi-aqueous half-air operating state and the target of the DC brushless motor is further if the current value of the current is lower than the first critical current value The rotational speed is set to a first predetermined rotational speed, wherein the first predetermined rotational speed is lower than a rated rotational speed of the direct current brushless motor.
A DC brushless motor system for a drain pump according to claim 13, wherein

The number of stator core slots is the same as the number of rotor poles, and the radial air gap formed by the rotor poles and the stator core is a non-uniform air gap.
A DC brushless motor system for a drain pump according to claim 13, wherein

The drive module includes an H-bridge inverter;

The control pulse signal output by the control module is a switch control pulse signal for controlling four switches in the H-bridge inverter.
A DC brushless motor system for a drain pump according to claim 13, wherein

When the DC brushless motor is in an idle operation state, a current value of a current flowing through a stator winding of the DC brushless motor is a first current value;

When the brushless DC motor is in a rated load operating state, a current value of a current flowing through a stator winding of the brushless DC motor is a second current value;

Wherein the first critical current value is higher than the first current value and lower than the second current value.
A DC brushless motor system for a drain pump according to claim 13, wherein said control module further applies said DC brushless motor if said current value of said current is lower than said second critical current value a target rotational speed set to a rated rotational speed of the brushless DC motor, the second critical current value being lower than the first critical current value and higher than the first current value, and the first critical current value and The second critical current value constitutes a current value interval of the semi-aqueous half air operating state.
A DC brushless motor system for a drain pump according to claim 13, wherein

The first predetermined rotational speed is 60-40% of the rated rotational speed of the brushless DC motor.
The DC brushless motor system for a drain pump according to claim 17, wherein the first predetermined rotational speed is 80%-60% of the rated rotational speed of the DC brushless motor;

The control module further sets a target rotational speed of the DC brushless motor to a second predetermined rotational speed, where the current value of the current is lower than the first intermediate current value, and the first intermediate current value is lower than The first critical current value is higher than the second critical current value, and the second predetermined rotational speed is lower than the first predetermined rotational speed and is 60-40% of the rated current of the brushless DC motor.