Air conditioning device

Abstract

The present invention relates to an air conditioning device. When a permanent magnet synchronous motor of the air conditioning device loses step, the actual motor rotor does not rotate, but is in a swinging state. At this time, the first power P1 calculated based on the actual voltage and current is very small; and the position estimated by the current and voltage through the position sensorless algorithm still thinks that the rotor is rotating, and the estimated speed ω1 cannot reflect the actual state of the rotor. Therefore, the second power P2 calculated by the speed ω1 is not the actual motor power, but is greater than the first power P1 at this time. Therefore, the present invention can determine whether the motor is out of step through the relationship between the first power P1 and the second power P2, and effectively detect the compressor out-of-step fault without adding external hardware circuits.

Description

Technical Field

[0001] The present invention relates to the technical field of air conditioning, and in particular to an air conditioning device for detecting motor step-out. Background Art

[0002] In air-conditioning devices, the main body of DC variable frequency compressors or DC variable frequency fans is a permanent magnet synchronous motor. Although permanent magnet synchronous motors have excellent characteristics such as energy saving, high efficiency, low noise, and stable operation compared to asynchronous motors, the operation of permanent magnet synchronous motors must keep the rotor and stator synchronized, otherwise there will be a step-out fault, resulting in the compressor or fan being unable to output, which will cause the compressor or fan to wear, heat, and even damage over a long period of time. At present, air-conditioning DC variable frequency compressors or DC variable frequency fans generally use a position sensorless control method, and can only estimate the position through the compressor or fan current, voltage, etc. through a position sensorless algorithm to ensure its operation. Once a step-out occurs, the compressor or fan voltage and current are not much abnormal, so the position estimated by the compressor or fan voltage and current is not greatly affected, which makes the step-out fault unable to be detected, and the motor will burn out if the step-out operation time is long. Summary of the invention

[0003] The present invention provides an air conditioning device, which solves the technical problem that a step-out fault of a permanent magnet synchronous motor of the air conditioning device cannot be detected.

[0004] In order to achieve the above object, the present invention adopts the following technical scheme:

[0005] An air conditioning device, comprising a permanent magnet synchronous motor, the air conditioning device further comprising:

[0006] A voltage acquisition module, used to acquire a d-axis voltage Vd and a q-axis voltage Vq; or used to acquire a voltage Vdc of a DC bus;

[0007] A current acquisition module, used to acquire a d-axis current id and a q-axis current iq; or used to acquire a current idc of a DC bus;

[0008] The motor speed estimation module is used to estimate the motor speed ω1 through a position sensorless algorithm;

[0009] A first power calculation module, used for calculating the first power P1 according to the d-axis voltage Vd, the q-axis voltage Vq, the d-axis current id and the q-axis current iq; or, used for calculating the first power P1 according to the voltage Vdc of the DC bus and the current idc of the DC bus;

[0010] A second power calculation module, used for calculating a second power P2 according to the motor speed ω1, the d-axis current id, the q-axis current iq, the d-axis inductance Ld and the q-axis inductance Lq of the motor;

[0011] The control module is used to determine that the motor is out of step when the out-of-step relationship is satisfied: the first power P1 is less than the second power P2.

[0012] An air conditioning device, comprising a permanent magnet synchronous motor, the air conditioning device further comprising:

[0013] A voltage acquisition module, used to acquire a d-axis voltage Vd and a q-axis voltage Vq; or used to acquire a voltage Vdc of a DC bus;

[0014] A current acquisition module, used to acquire a d-axis current id and a q-axis current iq; or used to acquire a current idc of a DC bus;

[0015] The motor speed estimation module is used to estimate the motor speed ω1 through a position sensorless algorithm;

[0016] A first torque calculation module, used for calculating the first torque T1 according to the d-axis voltage Vd, the q-axis voltage Vq, the d-axis current id, the q-axis current iq and the motor speed ω1; or, used for calculating the first torque T1 according to the DC bus voltage Vdc, the DC bus current idc and the motor torque ω1;

[0017] A second torque calculation module, used for calculating a second torque T2 according to the d-axis current id, the q-axis current iq, the d-axis inductance Ld and the q-axis inductance Lq of the motor;

[0018] The control module is used to determine that the motor is out of step when the out-of-step relationship is satisfied: the first torque T1 is less than the second torque T2.

[0019] The technical solution of the present invention has the following technical effects relative to the prior art: when the permanent magnet synchronous motor of the air-conditioning device of the present invention loses step, the actual motor rotor does not rotate, but is in a swinging state. At this time, the first power P1 calculated based on the actual voltage and current is very small; and the position estimated by the current and voltage through the position sensorless algorithm still thinks that the rotor is rotating, and the estimated speed ω1 cannot reflect the actual state of the rotor. Therefore, the second power P2 calculated by the speed ω1 is not the actual motor power, but is greater than the first power P1 at this time. Therefore, the present invention can determine whether the motor is out of step by the relationship between the first power P1 and the second power P2, and effectively detect the compressor out-of-step fault without adding external hardware circuits. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative work.

[0021] Figure 1 This is a principle block diagram of an air conditioning device according to a specific embodiment 1 of the present invention.

[0022] Figure 2 This is a flow chart of specific embodiment 1 of the present invention.

[0023] Figure 3 This is a principle block diagram of an air conditioning device according to a specific embodiment 2 of the present invention.

[0024] Figure 4 This is a flow chart of specific embodiment 2 of the present invention. DETAILED DESCRIPTION

[0025] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. 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.

[0026] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected" and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be directly connected or indirectly connected through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances. In the description of the above embodiments, specific features, structures, materials or characteristics can be combined in a suitable manner in any one or more embodiments or examples.

[0027] The terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "plurality" means two or more.

[0028] Embodiment 1

[0029] An air conditioning device comprises a permanent magnet synchronous motor, which can drive a compressor or a fan.

[0030] like Figure 1 As shown, the air conditioning device also includes a voltage acquisition module, a current acquisition module, a motor speed estimation module, a power calculation module and a control module.

[0031] The following is a detailed description of each module:

[0032] The current acquisition module is used to acquire the d-axis current id and the q-axis current iq. Specifically, the phase currents ia and ib are detected by current sensors, and the phase currents ia and ib are obtained by Clark transformation and Park transformation to obtain id and iq.

[0033] The voltage acquisition module is used to obtain the d-axis voltage Vd and the q-axis voltage Vq. Vd and Vq are calculated by adjusting the output of the d-axis and q-axis currents Pi.

[0034] The motor speed estimation module is used to estimate the motor speed ω1 through a position sensorless algorithm. The motor speed ω1 is estimated through a position sensorless algorithm. There are many position sensorless algorithms, such as sliding mode controller, Romberg, extended back electromotive force, flux observation, etc., which are all calculated through the motor model, and the physical quantities used are motor voltage, current, resistance, inductance and back electromotive force constant, etc. This embodiment does not restrict the estimation method of the motor speed ω1, and the existing technology can be used.

[0035] The first power calculation module is used to calculate the first power P1 according to the d-axis voltage Vd, the q-axis voltage Vq, the d-axis current id and the q-axis current iq.

[0036] Specifically, the first power P1 = 3 / 2×Pn×(Vq×iq+Vd×id) Formula (1).

[0037] Among them, Pn is the number of motor poles.

[0038] The second power calculation module is used to calculate the second power P2 according to the motor speed ω1, the d-axis current id, the q-axis current iq, the d-axis inductance Ld and the q-axis inductance Lq of the motor.

[0039] Specifically, the second power P2 = 3 / 2×Pn×(Ke×iq+(Ld−Lq)×idiq)×ω1 Formula (2).

[0040] Among them, Pn is the number of motor poles, and Ke is the back electromotive force constant of the motor.

[0041] The control module is used to determine whether the motor is out of step when the out-of-step relationship is met: the first power P1 is less than the second power P2.

[0042] When the permanent magnet synchronous motor operates normally, P1=P2.

[0043] 3 / 2×Pn×(Vq×iq+Vd×id) = 3 / 2×Pn×(Ke×iq+(Ld-Lq) ×idiq)×ω1 Equation (3)

[0044] Taking into account a certain error, P1 and P2 are approximately equal within a small error range.

[0045] When the permanent magnet synchronous motor loses step, the actual motor rotor does not rotate, but is in a swinging state. At this time, the power P1 calculated based on the actual voltage and current is very small. At this time, the position estimated by the current and voltage through the position sensorless algorithm still thinks that the rotor is rotating, and the estimated speed ω1 cannot reflect the actual state of the rotor. Therefore, the power P2 calculated by formula (2) is not the actual motor power, but is greater than the power P1 when it loses step. That is, when the permanent magnet synchronous motor loses step, P2 > P1.

[0046] Therefore, the power P1 calculated based on the actual voltage and current is compared with the power P2 calculated by the estimated speed. When the ratio or difference between the two is less than the preset value, that is, when equation (4) or equation (5) is satisfied, it can be determined as a loss of step.

[0047] Preferably, the control module is used to determine that the motor is out of step when the relationship between the first power P1 and the second power P2 satisfies P1-P2≤Perr formula (4), wherein Perr<0; or the control module is used to determine that the motor is out of step when the relationship between the first power P1 and the second power P2 satisfies P1 / P2≤Prate formula (5), wherein Prate<1.

[0048] Since different motors have different powers, the setting values ​​of Perr and Prate can be set to appropriate values ​​through experiments.

[0049] In order to further ensure the out-of-step judgment effect and avoid misjudgment, the control module is used to count the number of out-of-step times. When the number of out-of-step times is greater than the set value N, it is judged that the motor is out of step.

[0050] Specifically, the control module is used to increase the number of out-of-step times by 1 when the out-of-step relationship is met, and otherwise, decrease the number of out-of-step times by 1. The minimum out-of-step count is 0.

[0051] like Figure 2 As shown, the air conditioning device determines the out-of-step including the following steps:

[0052] S1. Start.

[0053] S2. Calculate the power P1 from the actual voltage and current using formula (1).

[0054] S3. Calculate the power P2 from the estimated speed using formula (2).

[0055] S4. Determine whether formula (3) or formula (4) is satisfied. If so, proceed to step S5. Otherwise, proceed to step S6.

[0056] S5, out-of-step count +1, go to step S7.

[0057] S6, out-of-step count -1, go to step S2.

[0058] S7. Determine if the out-of-step count is greater than N. If so, proceed to step S8; otherwise, proceed to step S2.

[0059] S8, shutdown due to loss of step.

[0060] S9. End.

[0061] Of course, the first power P1 of this embodiment is the actual power of the motor and can also be obtained through other ways. For example, the current acquisition module is used to obtain the current idc of the DC bus; the voltage acquisition module is used to obtain the voltage Vdc of the DC bus.

[0062] The first power calculation module is used to calculate the first power P1 according to the voltage Vdc of the DC bus and the current idc of the DC bus.

[0063] The first power P1 = Vdc×idc.

[0064] Embodiment 2

[0065] An air conditioning device includes a permanent magnet synchronous motor, which can drive a compressor or a fan.

[0066] like Figure 3 As shown, the air conditioning device also includes a voltage acquisition module, a current acquisition module, a motor speed estimation module, a torque calculation module and a control module.

[0067] The following is a detailed description of each module:

[0068] The current acquisition module is used to acquire the d-axis current id and the q-axis current iq. Specifically, the phase currents ia and ib are detected by current sensors, and the phase currents ia and ib are obtained by Clark transformation and Park transformation to obtain id and iq.

[0069] The voltage acquisition module is used to obtain the d-axis voltage Vd and the q-axis voltage Vq. Vd and Vq are calculated by adjusting the output of the d-axis and q-axis currents Pi.

[0070] The motor speed estimation module is used to estimate the motor speed ω1 through a position sensorless algorithm. The motor speed ω1 is estimated through a position sensorless algorithm. There are many position sensorless algorithms, such as sliding mode controller, Romberg, extended back electromotive force, flux observation, etc., which are all calculated through the motor model, and the physical quantities used are motor voltage, current, resistance, inductance and back electromotive force constant, etc. This embodiment does not restrict the estimation method of the motor speed ω1, and the existing technology can be used.

[0071] The first torque calculation module is used to calculate the first torque T1 according to the d-axis voltage Vd, the q-axis voltage Vq, the d-axis current id, the q-axis current iq and the motor speed ω1.

[0072] Specifically, the first torque T1 = 3 / 2×Pn×(Vq×iq+Vd×id) / ω1 Formula (6).

[0073] Among them, Pn is the number of motor poles.

[0074] The second torque calculation module is used to calculate the second torque T2 according to the d-axis current id, the q-axis current iq, the d-axis inductance Ld and the q-axis inductance Lq of the motor.

[0075] Specifically, the second torque T2 = 3 / 2×Pn×(Ke×iq + (Ld-Lq)×idiq) Formula (6).

[0076] Among them, Pn is the number of motor poles, and Ke is the back electromotive force constant of the motor.

[0077] The control module is used to determine whether the motor is out of step when the out-of-step relationship is satisfied: the first torque T1 is less than the second torque T2.

[0078] Preferably, the control module is used to determine that the motor is out of step when the relationship between the first torque T1 and the second torque T2 satisfies the formula T1-T2≤Terr (8), wherein Terr<0; or, the control module is used to determine that the motor is out of step when the relationship between the first torque T1 and the second torque T2 satisfies the formula T1 / T2≤Trate (9), wherein Trate<1.

[0079] In order to further ensure the out-of-step judgment effect and avoid misjudgment, the control module is used to count the number of out-of-step times. When the number of out-of-step times is greater than the set value N, it is judged that the motor is out of step.

[0080] Specifically, the control module is used to increase the number of out-of-step times by 1 when the out-of-step relationship is met, and otherwise, decrease the number of out-of-step times by 1. The minimum out-of-step count is 0.

[0081] like Figure 4 As shown, the air conditioning device determines the out-of-step including the following steps:

[0082] S1. Start.

[0083] S2, calculate the torque T1 from the actual voltage and current through formula (6).

[0084] S3. Calculate the torque T2 from the estimated rotation speed using equation (7).

[0085] S4. Determine whether formula (8) or formula (9) is satisfied. If so, proceed to step S5. Otherwise, proceed to step S6.

[0086] S5, out-of-step count +1, go to step S7.

[0087] S6, out-of-step count -1, go to step S2.

[0088] S7. Determine if the out-of-step count is greater than N. If so, proceed to step S8; otherwise, proceed to step S2.

[0089] S8, shutdown due to loss of step.

[0090] S9. End.

[0091] Of course, the first torque T1 of the present embodiment is the actual torque of the motor and can also be obtained through other means. For example, the current acquisition module is used to obtain the current idc of the DC bus; the voltage acquisition module is used to obtain the voltage Vdc of the DC bus.

[0092] The first torque calculation module is used to calculate the first torque T1 according to the voltage Vdc of the DC bus and the current idc of the DC bus.

[0093] The first torque T1 = Vdc×idc / ω1.

[0094] The above are only specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed by the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. An air conditioning device, comprising a permanent magnet synchronous motor, characterized in that: The air conditioning device further comprises: A voltage acquisition module, used to acquire a d-axis voltage Vd and a q-axis voltage Vq; or used to acquire a voltage Vdc of a DC bus; A current acquisition module, used to acquire a d-axis current id and a q-axis current iq; or used to acquire a current idc of a DC bus; The motor speed estimation module is used to estimate the motor speed ω1 through a position sensorless algorithm; A first power calculation module, used for calculating the first power P1 according to the d-axis voltage Vd, the q-axis voltage Vq, the d-axis current id and the q-axis current iq; or, used for calculating the first power P1 according to the voltage Vdc of the DC bus and the current idc of the DC bus; A second power calculation module, used for calculating a second power P2 according to the motor speed ω1, the d-axis current id, the q-axis current iq, the d-axis inductance Ld and the q-axis inductance Lq of the motor; A control module, configured to determine that the motor is out of step when the out-of-step relationship is satisfied: the first power P1 is less than the second power P2; The first power P1 = 3 / 2×Pn×(Vq×iq+Vd×id), or the first power P1 = Vdc×idc; the second power P2 = 3 / 2×Pn×(Ke×iq+(Ld-Lq) ×idiq)×ω1; wherein Pn is the number of motor poles, and Ke is the back electromotive force constant of the motor.

2. The air conditioning device according to claim 1, characterized in that: The control module is used to determine that the motor is out of step when the relationship between the first power P1 and the second power P2 satisfies P1-P2≤Perr, where Perr<0; or, the control module is used to determine that the motor is out of step when the relationship between the first power P1 and the second power P2 satisfies P1 / P2≤Prate, where Prate<1.

3. The air conditioning device according to any one of claims 1 to 2, characterized in that: The control module is used to count the number of out-of-step times, and when the number of out-of-step times is greater than a set value N, it is determined that the motor is out of step.

4. The air conditioning device according to claim 3, characterized in that: The control module is used for increasing the number of out-of-step times by 1 when the out-of-step relationship is met, and decreasing the number of out-of-step times by 1 otherwise.

5. An air conditioning device, comprising a permanent magnet synchronous motor, characterized in that: The air conditioning device further comprises: A voltage acquisition module, used to acquire a d-axis voltage Vd and a q-axis voltage Vq; or used to acquire a voltage Vdc of a DC bus; A current acquisition module, used to acquire a d-axis current id and a q-axis current iq; or used to acquire a current idc of a DC bus; The motor speed estimation module is used to estimate the motor speed ω1 through a position sensorless algorithm; A first torque calculation module, used for calculating the first torque T1 according to the d-axis voltage Vd, the q-axis voltage Vq, the d-axis current id, the q-axis current iq and the motor speed ω1; or, used for calculating the first torque T1 according to the DC bus voltage Vdc, the DC bus current idc and the motor torque ω1; A second torque calculation module, used for calculating a second torque T2 according to the d-axis current id, the q-axis current iq, the d-axis inductance Ld and the q-axis inductance Lq of the motor; A control module, configured to determine that the motor is out of step when the out-of-step relationship is satisfied: the first torque T1 is less than the second torque T2; The first torque T1 = 3 / 2×Pn×(Vq×iq+Vd×id) / ω1, or, the first torque T1 = Vdc×idc / ω1; the second torque T2 = 3 / 2×Pn×(Ke×iq + (Ld-Lq) ×idiq); wherein Pn is the number of motor poles, and Ke is the back electromotive force constant of the motor.

6. The air conditioning device according to claim 5, characterized in that: The control module is used to determine that the motor is out of step when the relationship between the first torque T1 and the second torque T2 satisfies T1-T2≤Terr, where Terr<0; or, the control module is used to determine that the motor is out of step when the relationship between the first torque T1 and the second torque T2 satisfies T1 / T2≤Trate, where Trate<1.

7. The air conditioning device according to any one of claims 5 to 6, characterized in that: The control module is used to count the number of out-of-step times, and when the number of out-of-step times is greater than a set value N, it is determined that the motor is out of step.

8. The air conditioning device according to claim 7, characterized in that: The control module is used for increasing the number of out-of-step times by 1 when the out-of-step relationship is met, and decreasing the number of out-of-step times by 1 otherwise.

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