Motor phase current lead angle control circuit, direct current inner fan controller and air conditioner

Abstract

The application discloses a motor phase current lead angle control circuit, a direct current inner fan controller and an air conditioner. The motor phase current lead angle control circuit comprises a first resistor, a switching device, a second resistor and a third resistor. The first end of the first resistor is connected with a speed regulation signal input end. The first end of the switching device is connected with the second end of the first resistor, and the second end of the switching device is connected with the speed regulation signal input end. The first end of the second resistor is connected with the first end of the switching device and the second end of the first resistor, and the second end of the second resistor is grounded. The first end of the third resistor is connected with a lead angle signal input end and the third end of the switching device, and the second end of the third resistor is grounded. Thus, the switching state of the switching device can be controlled by changing the VSP input voltage, so that the LA input voltage V LA is changed, the motor is operated at different lead angles under different V sp , and the problem that the electromagnetic noise is large during the operation of the motor at a low speed stage is solved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of electrical equipment, in particular to a motor phase current lead angle control circuit, a direct current inner fan controller and an air conditioner. BACKGROUND

[0002] Efficiency and noise are important indicators for measuring the performance of motor products. It is costly and time-consuming to improve the above performance indicators from the structure of the motor itself, so the improvement is usually made from control.

[0003] Motor drive dedicated chips are widely used in the design of air conditioner direct current inner fan controllers due to their high integration and short development cycle. Chip manufacturers usually design pins that can adjust the output power of the motor to solve the problem of product energy efficiency. Since the motor is a resistive and inductive load, the phase current will slowly rise to the target value when the excitation voltage is applied to the two ends of the sub-coil. By controlling the phase of the phase current leading the counter potential, the two phases are made to be in phase, at which time the motor output power is maximum and the optimal output efficiency is achieved.

[0004] The common lead angle control methods include fixed lead angle control and lead angle control following the change of the speed signal VSP. Since the air conditioner fan blades have a swing blowing condition (i.e. variable load condition), the fixed lead angle cannot meet the demand of outputting maximum power under different speeds and loads. The most widely used method in the lead angle control following the change of the speed signal VSP is the linear follow-up of the lead angle speed command VSP signal. However, this scheme will have a large speed fluctuation in the low speed section, which will directly affect the user's experience. SUMMARY

[0005] Therefore, the motor phase current lead angle control circuit is provided to solve the problem of large electromagnetic noise of the motor in the low speed section in the conventional lead angle control method following the change of the speed signal VSP.

[0006] According to a first aspect, the motor phase current lead angle control circuit comprises a first resistor, a switching device, a second resistor and a third resistor. The first end of the first resistor is connected with a speed signal input end (i.e. a speed signal input pin). The first end of the switching device is connected with the second end of the first resistor, and the second end of the switching device is connected with the speed signal input end. The first end of the second resistor is connected with the first end of the switching device and the second end of the first resistor, and the second end of the second resistor is grounded. The first end of the third resistor is connected with a lead angle signal input end and the third end of the switching device, and the second end of the third resistor is grounded.

[0007] With reference to the first aspect, in a first implementation of the first aspect, the motor phase current lead angle control circuit further comprises a fourth resistor, a first end of the fourth resistor being connected with the speed regulation signal input end, and a second end of the fourth resistor being connected with a first end of the first resistor.

[0008] With reference to the first implementation of the first aspect, in a second implementation of the first aspect, the motor phase current lead angle control circuit further comprises a fifth resistor, a first end of the fifth resistor being connected with the lead angle signal input pin and a third end of the switching device, and a second end of the fifth resistor being connected with a first end of the third resistor.

[0009] With reference to the first aspect, in a third implementation of the first aspect, the motor phase current lead angle control circuit further comprises a sixth resistor, a first end of the sixth resistor being connected with the speed regulation signal input end, and a second end of the sixth resistor being connected with a third end of the switching device.

[0010] With reference to the first aspect, in a fourth implementation of the first aspect, the switching device is a triode, a first end of the switching device being a control end of the triode, a second end of the switching device being an input end of the triode, and a third end of the switching device being an output end of the triode.

[0011] With reference to the first aspect, in a fifth implementation of the first aspect, a resistance value of the second resistor is determined according to a demarcation value of the motor phase current lead angle.

[0012] With reference to the second implementation of the first aspect, in a sixth implementation of the first aspect, a resistance value of the fourth resistor is smaller than a sum of resistance values of the fifth resistor and the third resistor.

[0013] With reference to the first aspect, in the fifth implementation of the first aspect, a voltage of the speed regulation signal input end is 2.1V-5.4V.

[0014] According to the second aspect, the embodiment of the present application further provides a direct-current inner fan controller, comprising the motor phase current lead angle control circuit of the first aspect or any implementation of the first aspect.

[0015] According to the second aspect, the embodiment of the present application further provides an air conditioner, comprising the direct-current inner fan controller of the second aspect.

[0016] The motor phase current lead angle control circuit, the direct-current inner fan controller and the air conditioner provided by the embodiment of the present application can control the switching state of the switching device by changing the VSP input voltage, thereby changing the LA input voltage V LA , i.e. the lead angle of the phase current lead back electromotive force phase, so that the motor is in different V spBy operating at different lead angles, the problem of high electromagnetic noise during low-speed motor operation can be solved. Attached Figure Description

[0017] The features and advantages of the invention will be more clearly understood by referring to the accompanying drawings, which are schematic and should not be construed as limiting the invention in any way. In the drawings:

[0018] Figure 1 The diagram shows the peripheral circuit of the LA pin before optimization;

[0019] Figure 2 This is a schematic diagram of the motor phase current lead angle control circuit in Embodiment 1 of the present invention;

[0020] Figure 3 This is a schematic diagram showing the adjustment of Vsp during the transistor's conduction time.

[0021] Figure 4 This is a plot of the measured data. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0023] Example 1

[0024] Figure 1 To optimize the previous LA pin peripheral circuit diagram, in Figure 1 In the diagram, LA is the lead angle signal input pin, and VSP is the speed control signal input pin. Figure 1 As shown, V LA / V sp =R2 / (R 限流 The value of (+R1+R2) is fixed, i.e., ΔV LA The performance remained essentially unchanged across all speed ranges. Actual measurements revealed that this design performed well at low speeds (e.g., 2.1V ≤ V). sp When the voltage is ≤2.9V, the motor speed fluctuates greatly and the electromagnetic noise is relatively high.

[0025] Analysis revealed that when the motor operates at low speeds, the phase current rises to the target value relatively quickly. If a large lead angle is given (after the Hall waveform flips), the rotor magnetic field needs to rotate through a larger angle to be attracted by the stator magnetic field during commutation. This results in a decrease in the motor's electromagnetic torque T. e Large fluctuations, as shown by formula P 输出 =Te As can be seen from Ω, the speed fluctuation increases as the power remains constant.

[0026] Specifically, since multiple components within the wall-mounted air conditioner require power, a power supply mainboard is designed, with all power supplies integrated onto it. The input terminal signals (VDC power input, VSP speed control signal, etc.) of the built-in driver board for the indoor fan (blower motor) all require power from the mainboard. The input voltage range of the VSP pin is related to the VSP-related program within the mainboard. Therefore, when the VSP pin input voltage is between 2.1V and 5.4V, the PWM duty cycle of the chip's control input winding changes linearly. That is, across the entire motor speed range, the LA pin input voltage V... LA Follow the input voltage V on the VSP pin sp It exhibits a linear change.

[0027] Based on this, Embodiment 1 of the present invention provides a motor phase current lead angle control circuit. For example... Figure 2 As shown, the motor phase current lead angle control circuit includes a first resistor (R3), a switching device (Q1), a second resistor (R4), and a third resistor (R7). Specifically, the first terminal of the first resistor (R3) is connected to the speed control signal input terminal (i.e., the speed control signal input pin); the first terminal of the switching device (Q1) is connected to the second terminal of the first resistor (R3), and the second terminal of the switching device (Q1) is connected to the speed control signal input terminal; the first terminal of the second resistor (R4) is connected to the first terminal of the switching device (Q1) and the second terminal of the first resistor (R3), and the second terminal of the second resistor (R4) is grounded; the first terminal of the third resistor (R7) is connected to the lead angle signal input terminal (i.e., the lead angle signal input pin) and the third terminal of the switching device (Q1), and the second terminal of the third resistor (R7) is grounded.

[0028] Therefore, the aforementioned motor phase current lead angle control circuit can change the switching state of the control switching device (Q1) by changing the VSP input voltage, thereby changing the LA input voltage V. LA That is, the lead angle of the phase current leading the back electromotive force phase, which causes the motor to have different V sp By operating at different lead angles, the problem of high electromagnetic noise during low-speed motor operation can be mitigated. In other words, this is achieved by controlling the switching state of transistor Q1: the input voltage V at the LA pin is adjusted according to the motor's speed range. LA Follow the input voltage V of the VSP pin with different variations sp Make changes.

[0029] For example, the following can be achieved by switching the device (Q1) on and off: (1) at low speed (2.1V≤V) sp≤ 2.9V), the transistor works in off state, V LA / V sp = R7 / (R 限流 + R5+ R6+ R7), a small lead angle command signal is given; (2) in high speed section (2.9V < V sp ≤ 5.4V), the transistor works in on state, V LA / V sp = R7 / (R 限流 + R6+ R7), compared with the same speed section AV LA change is small, that is, a large lead angle command signal is given; (3) when VSP pin input voltage V sp = 5.4V, the lead angle reaches the maximum phase of chip design, at this time, LA pin input voltage V LA = 5V.

[0030] Further, the motor phase current lead angle control circuit further comprises a fourth resistor (R 限流 ), a first end of the fourth resistor (R 限流 ) is connected with the speed signal input end, and a second end of the fourth resistor (R 限流 ) is connected with a first end of the first resistor (R3).

[0031] Specifically, the fourth resistor avoids that the voltage value of the VSP given by the mainboard is too large, causing damage to the internal circuit related to the VSP pin of the chip. Usually, a small resistance value, such as 1kΩ, is taken.

[0032] Further, the motor phase current lead angle control circuit further comprises a fifth resistor (R6), a first end of the fifth resistor (R6) is connected with the lead angle signal input pin, a third end of the switching device (Q1) and a second end of the sixth resistor (R5), and a second end of the fifth resistor (R6) is connected with a first end of the third resistor (R7).

[0033] This is because the fourth resistor (R 限流 ) usually takes a small resistance value, and if there is no R6 in the circuit, when the transistor is turned on, R5 is equivalent to being connected in parallel with the wire, the LA pin input voltage V LA = V sp *R7 / (R7+R 限流 ), the resistance value of R 限流 is much smaller than R7, V LA / V SP = 1, and the lead angle cannot be changed.

[0034] Furthermore, the motor phase current lead angle control circuit also includes a sixth resistor (R5), the first end of which is connected to the speed control signal input terminal, and the second end of which is connected to the third end of the switching device (Q1).

[0035] Specifically, the switching device (Q1) is a transistor, the first terminal of the switching device (Q1) is the control terminal of the transistor, the second terminal of the switching device (Q1) is the input terminal of the transistor, and the third terminal of the switching device (Q1) is the output terminal of the transistor.

[0036] It should be noted that the voltage divider ratio at the input terminal of transistor Q1, R4, can control the boundary V of the lead angle. sp The output voltage divider ratio of R7 can control the distinction between large and small lead angles, while ensuring V. sp =5.4V LA =5V.

[0037] First, let's analyze how to determine the boundary V of the lead angle. sp For the sake of simplifying calculations, let's assume R = ... 限流 Much smaller than (R3+R4) and the turn-on voltage V of transistor Q1 on =0.7V, then:

[0038] V sp -R4 / (R3+R4)*V sp =0.7V

[0039] When V spth When the voltage is 2.9V, the transistor is in the ON state, and the voltage division ratio of R4 can be calculated at this time. as follows:

[0040]

[0041] Because the above analysis ignores R 限流 Resistor voltage divider: During actual testing, it was found that when the resistor values ​​at the transistor input terminal were proportional as shown in the above formula, V... spth The transistor is already in the ON state when the voltage is <2.9V. (Using V...) sp The x-axis is represented by V. sp / V sp , Plotting the vertical axis Figure 3 In the picture That is, the emitter-base voltage drop when the transistor is turned on. Figure 3 In the diagram, kR4 = B corresponds to the dotted line above, and kR4 = A corresponds to the dashed line below. Figure 3 It can be seen that increasing the partial voltage ratio of R4 (e.g.) Figure 3 (As shown by the dashed line in the middle) can increase the V when the transistor is turned on.spth , now need to make V spth = 2.9V triode open.

[0042] It should be noted that when the measured triode conduction V sp is greater than the threshold V spth , the value of the triode input R4 / (R3+R4) is reduced, and when V sp is greater than the threshold V spth , the above ratio is increased.

[0043] In the embodiment 1 of the application, the resistance value of the second resistor (R4) is determined according to the threshold value of the motor phase current lead angle. That is, when the threshold Vsp value (i.e. V spth ) is determined, the R4 voltage division value can be derived by the above formula, and then the appropriate R3 and R4 resistance values are selected. In the embodiment 1 of the application, Vspth=2.9V is the optimal Vsp threshold for switching the size of the lead angle control found during the initial development process using a fixed lead angle control circuit (such as Figure 1 ), so after using the improved circuit of the application, Vspth is a value that has been determined, and only the R4 voltage division value needs to be derived by the following formula to determine reasonable R4 and R3 resistance values.

[0044] Secondly, analyze how to control the degree of differentiation of the size of the lead angle (the degree of differentiation distinguishes whether the phase is large or small, the size of the lead angle) and ensure that V sp reaches the maximum V spmax , the lead angle reaches the upper limit of the chip design. To simplify the calculation, it is assumed that R 限流 is much smaller than (R6+R7), when the motor runs in the low speed section (2.1V≤V sp ≤2.9V), the input chip LA pin voltage V LA is as follows:

[0045] V LA =R7 / (R5+R6+R7)*Vsp

[0046] When the motor runs in the high speed section (2.9V sp ≤5.4V), the V LA is as follows:

[0047] V LA =R7 / (R6+R7)*Vsp

[0048] At the same time, it needs to be ensured that:

[0049] R7 / (R6+R7)=5 / 5.4≈0.93

[0050] From the above two formulas, it can be seen that increasing the resistance values of R5 and R7 appropriately can increase the distinction of the size of the leading angle, so as to avoid the speed fluctuation problem caused by the large leading angle in the low speed section.

[0051] The measured data of the scheme R3=15kΩ, R4=100kΩ, R5=510kΩ, R6=43kΩ, R7=510kΩ are shown in the dot plot with V Figure 4 as the horizontal coordinate and V sp as the vertical coordinate. LA sp As can be seen from the figure, when 2.1V≤V sp ≤2.9V, V LA / V sp is a constant ratio,

[0052] When 2.9V<V sp ≤3.8V, the triode works in the amplification zone, and the output current i C of the triode Q1 changes approximately linearly with the input current i B .

[0053] When 2.9V<V sp ≤3.8V, the triode works in the saturation zone, and the output current i C is limited by the external circuit, and V LA / V sp is a large ratio, that is, the change amount of the leading angle in the high speed section is larger than that in the low speed section at the same two speed points, so that the large and small leading angles are distinguished.

[0054] As can be seen, the motor phase current leading angle control circuit provided by the embodiment 1 of the application can realize the following functions:

[0055] 1. By changing the V sp SP pin input voltage, the switching state of the triode is controlled, so that the LA pin input voltage V LA , that is, the leading angle of the phase current leading potential phase, is changed, so that the motor runs at different leading angles under different V sp .

[0056] 2. By changing the ratio , the V spth SP pin input signal voltage threshold when the triode Q1 is turned on is controlled, so that the large and small leading angle switching conditions are controlled.

[0057] 3. According to the R7 voltage division resistance value R7 / (R 限流 +R5+R6+R7)*V sp when the triode Q1 is turned off, the phase current leading small phase when the motor runs in the low speed section can be calculated; according to the R7 voltage division resistance value R7 / (R​限流 +R6+R7)*V sp , the phase current of the motor operating in the high speed section can be calculated to be ahead of a large phase;

[0058] 4, when VSP speed instruction reaches target voltage value V spmax , R7 voltage divider R7 / (R 限流 +R6+R7)*V spmax The actual lead angle can reach the maximum lead angle of the special chip.

[0059] Embodiment 2

[0060] On the basis of the embodiment 1 of the present application, the embodiment 2 of the present application further provides a direct current inner fan controller, and the motor phase current lead angle control circuit provided by the embodiment 1.

[0061] Further, the embodiment 2 of the present application further provides an air conditioner, which comprises the direct current inner fan controller.

[0062] Although the embodiments of the present application are described in conjunction with the drawings, various modifications and changes can be made by those skilled in the art without departing from the spirit and scope of the present application, and such modifications and changes fall within the scope defined by the appended claims.

Claims

1. A motor phase current lead angle control circuit, characterized by, The motor phase current lead angle control circuit comprises: a first resistor, a first end of the first resistor being connected with a second end of a fourth resistor; a first end of the fourth resistor being connected with a speed regulation signal input end, and a second end of the fourth resistor being connected with a first end of the first resistor; a switching device, a first end of the switching device being connected with a second end of the first resistor, and a second end of the switching device being connected with the first end of the first resistor; a second resistor, a first end of the second resistor being connected with the first end of the switching device and the second end of the first resistor, and a second end of the second resistor being grounded; a sixth resistor, a first end of the sixth resistor being connected with the first end of the first resistor, and a second end of the sixth resistor being connected with a third end of the switching device and a first end of a fifth resistor; a fifth resistor, a first end of the fifth resistor being connected with the second end of the sixth resistor and the third end of the switching device, and a second end of the fifth resistor being connected with a first end of a third resistor and outputting a phase current lead angle; a third resistor, a first end of the third resistor being connected with the second end of the fifth resistor, and a second end of the third resistor being grounded. The third end of the switching device, the second end of the sixth resistor, and the first end of the fifth resistor are connected to the same node in the circuit, and the voltage of the speed regulation signal input end is 2.1V-5.4V.

2. The motor phase current lead angle control circuit of claim 1, wherein, The switching device is a triode, the first end of the switching device is a control end of the triode, the second end of the switching device is an input end of the triode, and the third end of the switching device is an output end of the triode.

3. The motor phase current lead angle control circuit of claim 1, wherein, The resistance value of the second resistor is determined according to the demarcation value of the motor phase current lead angle.

4. The motor phase current lead angle control circuit of claim 1, wherein, The resistance value of the fourth resistor is smaller than the sum of the resistance values of the fifth resistor and the third resistor.

5. A direct current inline fan controller characterized by, The motor phase current lead angle control circuit comprises the motor phase current lead angle control circuit according to any one of claims 1-4.

6. An air conditioner characterized by comprising: The direct current inner fan controller comprises the direct current inner fan controller according to claim 5.

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