RELATED APPLICATIONS

This application claims priority to Taiwan Application Serial Number 102128403, filed Aug. 8, 2013, which is herein incorporated by reference.

BACKGROUND

1. Field of Invention

The present disclosure relates to an estimating method for a rotor position of a motor and an estimating device for the same.

2. Description of Related Art

With advances in technology, motors are widely used in our daily lives. For example, motors are used in hard disks, air conditioners, cranes, and so on.

A permanent magnet synchronous motor (PMSM) includes a plurality of stators and a rotor. The stators can be fabricated by wires, and are disposed around the rotor. The rotation of the rotor can be controlled by controlling currents applied to the stators.

In a control (or an activation) of the PMSM, it is necessary to first estimate the rotor position of the PMSM, after which the currents can be provided to the stators to rotate the rotor according to the estimated rotor position of the PMSM. If there is a large deviation between the estimated rotor position and an actual rotor position, the rotor may rotate in the wrong rotational direction or control of the PMSM may fail, resulting in operational instability of the PMSM.

Thus, an estimating method for accurately estimating the rotor position of a motor is desired.

SUMMARY

One aspect of the present invention is directed to an estimating method for a rotor position of a motor. In accordance with one embodiment of the present invention, the estimating method includes injecting a first high frequency signal to the motor at a first estimating angle, generating a first sensing signal of the motor in a period when the first high frequency signal is injected to the motor, injecting a second high frequency signal to the motor at a second estimating angle, generating a second sensing signal of the motor in a period when the second high frequency signal is injected to the motor, determining a quadrant of an operating angle according to the first sensing signal and the second sensing signal, and acquiring the rotor position according to the first sensing signal, the second sensing signal, and the quadrant of the operating angle. The second estimating angle is different from the first estimating angle. The operating angle is twice as large as an angle difference between the first estimating angle and the rotor position.

Another aspect of the present invention is directed to an estimating device for estimating a rotor position of a motor. In accordance with one embodiment of the present invention, the estimating device is electrically connected to the motor. The estimating device includes a high frequency signal injection module, a sensing module, and a calculating module. The high frequency signal injection module is configured to inject a first high frequency signal to the motor at a first estimating angle, and inject a second high frequency signal to the motor at a second estimating angle. The second estimating angle is different from the first estimating angle. The sensing module is configured to generate a first sensing signal of the motor in a period when the first high frequency signal is injected to the motor, and generate a second sensing signal of the motor in a period when the second high frequency signal is injected to the motor. The calculating module is configured to determine a quadrant of an operating angle according to the first sensing signal and the second sensing signal, and acquire the rotor position according to the first sensing signal, the second sensing signal, and the quadrant of the operating angle. The operating angle is twice as large as an angle difference between the first estimating angle and the rotor position.

Thus, through application of one of the embodiments mentioned above, the estimating device can rapidly determine the quadrant of the operating angle according to the first sensing signal and the second sensing signal, so as to acquire the rotor position. Through such operation, the stability of the motor can be effectively increased.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention can be more fully understood by reading the following detailed description of the embodiment, with reference made to the accompanying drawings as follows:

FIG. 1 is a schematic diagram of an estimating device in accordance with one embodiment of the present disclosure;

FIG. 2 is a schematic diagram of a high frequency signal injection module, a sensing module, and a calculating module in the estimating device in accordance with one embodiment of the present disclosure; and

FIG. 3 is a flow chart of an estimating method in accordance with one embodiment of the present disclosure.

DETAILED DESCRIPTION

In the following detailed description, for purposes of explanation, numerous specific details are set forth in order to attain a thorough understanding of the disclosed embodiments. It will be apparent, however, that one or more embodiments may be practiced without these specific details. In other instances, well-known structures and devices are schematically shown in order to simplify the drawing.

It will be understood that, although the terms first, second, etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. For example, a first element could be termed a second element, and, similarly, a second element could be termed a first element, without departing from the scope of the embodiments.

It will be understood that when an element is referred to as being â€œconnectedâ€ or â€œcoupledâ€ to another element, it can be directly connected or coupled to the other element or intervening elements may be present. In contrast, when an element is referred to as being â€œdirectly connectedâ€ or â€œdirectly coupledâ€ to another element, there are no intervening elements present. Moreover, â€œelectrically connectâ€ or â€œconnectâ€ can further refer to the interoperation or interaction between two or more elements.

Any element in a claim that does not explicitly state â€œmeans forâ€ performing a specified function, or â€œstep forâ€ performing a specific function, is not to be interpreted as a â€œmeansâ€ or â€œstepâ€ clause as specified in 35 U.S.C. Â§112, 6th paragraph. In particular, the use of â€œstep ofâ€ in the claims herein is not intended to invoke the provisions of 35 U.S.C. Â§112, 6th paragraph.

One aspect of the present invention is an estimating device for estimating a rotor position of a motor. To facilitate the description to follow, reference is made to FIG. 1 and FIG. 2, in which FIG. 1 is a schematic diagram of an estimating device 100 in accordance with one embodiment of the present disclosure, and FIG. 2 is a schematic diagram of a high frequency signal injection module 110, a sensing module 120, and a calculating module 130 in the estimating device 100 in accordance with one embodiment of the present disclosure.

The estimating device 100 is electrically connected to a motor 10 and an inverter 20, and is configured to estimate a rotor position (or a rotor angle) 0 of a rotor of the motor 10. The estimating device 100 can be realized by a computer or a circuit assembly. The motor 10 can be a permanent magnet synchronous motor (PMSM). The inverter 20 can be realized by a plurality of transistors.

In this embodiment, the estimating device 100 includes the high frequency signal injection module 110, the sensing module 120, the calculating module 130, and a determining module 140. The high frequency signal injection module 110, the sensing module 120, the calculating module 130, the determining module 140, the inverter 20, and the motor 10 can be electrically connected to each other. Each of the high frequency signal injection module 110, the sensing module 120, the calculating module 130, and the determining module 140 can be realized by software or hardware.

It should be noted that the ways in which the estimating device 100, the motor 10, the inverter 20, the high frequency signal injection module 110, the sensing module 120, the calculating module 130, and the determining module 140 are realized are not limited by the embodiments described above. In addition, the connections among these devices and modules are not limited by the embodiments described above. Any configuration of these devices and interconnections thereamong that would enable the estimating device 100 to practice the technical features described below can be used herein.

In this embodiment, the high frequency signal injection module 110 is configured to inject a first high frequency signal f₁₁to the motor 10 at a first estimating angle {circumflex over (Î¸)}₁through the inverter 20, as illustrated in FIG. 2. In one embodiment, the high frequency signal injection module 110 can provide first space vector pulse width modulation (SVPWM) signals v_Î±3c, v_Î²1c, to the inverter 20 to make the inverter 20 generate stator currents i_U1, i_V1, i_W1, and provide the stator currents i_U1, i_V1, i_W1, to the motor 20. In addition, the high frequency signal injection module 110 is further configured to inject a second high frequency signal f₁₂to the motor 10 at a second estimating angle (or a disturbing angle) {circumflex over (Î¸)}₂through the inverter 20. In one embodiment, the high frequency signal injection module 110 can provide second SVPWM signals v_Î±2c, v_Î²2c, to the inverter 20 to make the inverter 20 generate stator currents i_U2, i_V2, i_W2, and provide the stator currents i_U2, i_V2, i_W2, to the motor 20. In this embodiment, the second estimating angle {circumflex over (Î¸)}₂is different from the first estimating angle {circumflex over (Î¸)}₁. Moreover, in one embodiment, there is a tiny disturbing difference between the first estimating angle {circumflex over (Î¸)}₁and the second estimating angle {circumflex over (Î¸)}₂.

The sensing module 120 is configured to sense the stator currents i_U2, i_V1, i_W1, on the motor 10 and generate a first sensing signal (e.g., at least one of response currents Ã®_d1, Ã®_q1, of the motor 10) according to the stator currents i_U1, i_V1, i_W1, in the period when the high frequency signal injection module 110 injects the first high frequency signal f₁₁to the motor 10. In addition, the sensing module 120 is further configured to sense the stator currents i_U2, i_V2, i_W2on the motor 10 and generate a second sensing signal (e.g., at least one of response currents Ã®_d2, Ã®_q2of the motor 10) according to the stator currents i_U2, i_V2, i_W2, in the period when the high frequency signal injection module 110 injects the second high frequency signal f₁₂to the motor 10.

The calculating module 130 is configured to acquire values of a sine function of an operating angle Ï† and a cosine function of the operating angle Ï† according to the first sensing signal and the second sensing signal, and determine a quadrant of the operating angle Ï† according to whether each of the values of the sine function of the operating angle Ï† and the cosine function of the operating angle Ï† is a positive number or a negative number. In this embodiment, the operating angle Ï† corresponds to an angle difference Î”Î¸₁between the first estimating angle {circumflex over (Ï†)}₁and the rotor position Î¸ (e.g., Î”Î¸₁=Î¸âˆ’{circumflex over (Î¸)}₁). In one embodiment, the operating angle is twice as large as the angle difference Î”Î¸₁between the first estimating angle {circumflex over (Î¸)}₁and the rotor position Î¸ (e.g., Ï†=2Ã—Î”Î¸₁).

Subsequently, the calculating module 130 is configured to calculate the value of the operating angle Ï† through an inverse trigonometric function according to the values of the sine function of the operating angle Ï† and the cosine function of the operating angle Ï†. Next, the calculating module 130 is configured to calculate a value of the rotor position Î¸ according to the operating angle Ï†, the quadrant of the operating angle Ï†, and the first estimating angle Ï†.

After the value of the rotor position Î¸ is calculated, the determining module 140 is configured to determine a direction of a magnetic north pole of the rotor of the motor 10 using a pulse injection method. Hence, the rotor position Î¸ of the motor 10 can be ascertained.

To better explain the estimating device 100, one exemplary embodiment thereof is described in the following paragraphs. However, the invention is not limited by the exemplary embodiment described below.

In this exemplary embodiment, in a period when the high frequency signal injection module 110 injects the first high frequency signal f₁₁with a value U_icos Ï‰_it (U_iand Ï‰_ican be regarded as constants herein) to a d-axis of the motor 10 at the first estimating angle {circumflex over (Î¸)}₁, the sensing module 120 can sense the stator currents i_U1, i_V1, i_W1, on the motor 10, and accordingly generate the response current Ã®_d1on the d-axis of the motor 10 and the response current Ã®_q1on the q-axis of the motor 10. Values of the response currents Ã®_d1, Ã®_q1can be presented as the following equation:

$\begin{matrix} [\begin{matrix} {\hat{i}}_{d î¢ž î¢ž 1} \\ {\hat{i}}_{q î¢ž î¢ž 1} \end{matrix}] = [\begin{matrix} \frac{U_{i} î¢ž î¢ž \sin î¢ž î¢ž {Ï‰}_{i} î¢ž t}{{Ï‰}_{i} î¢ (L^{2} - Î” î¢ž î¢ž L^{2})} î¢ž (L - Î” î¢ž î¢ž L î¢ž î¢ž \cos î¢ž î¢ž 2 î¢ž î¢ž Î”Î¸ î¢ž î¢ž 1) \\ \frac{- U_{i} î¢ž î¢ž \sin î¢ž î¢ž {Ï‰}_{i} î¢ž t}{{Ï‰}_{i} î¢ (L^{2} - Î” î¢ž î¢ž L^{2})} î¢ž Î” î¢ž î¢ž L î¢ž î¢ž \sin î¢ž î¢ž 2 î¢ž î¢ž Î”Î¸ î¢ž î¢ž 1 î¢ž \end{matrix}] & Eq î¢ž î¢ž (1) \end{matrix}$

In Eq(1), L and Î”L can be regarded as constants herein.

The calculating module 130 samples the response current Ã®_q1and mixes (or multiplies) the response current Ã®_q1with a high frequency carrier f_chaving a value sin Ï‰_it to generate a first mixing signal m1. Subsequently, the calculating module 130 low-pass filters the first mixing signal m1 to acquire a first calculating value f_Î”Î¸1. The first calculating value f_Î”Î¸1can be presented by the following equation:

$\begin{matrix} f_{Î”Î¸ î¢ž î¢ž 1} = k î¢ž î¢ž \sin î¢ž î¢ž 2 î¢ž î¢ž Î”Î¸ î¢ž î¢ž 1, k = \frac{- U_{i}}{2 î¢ž î¢ž {Ï‰}_{i} î¢ (L^{2} - Î” î¢ž î¢ž L^{2})} î¢ž Î” î¢ž î¢ž L & Eq î¢ž î¢ž (2) \end{matrix}$

Through the equation above, the value of the sine function of the angle 2Î”Î¸1 can be acquired, that is, the value of the sine function of the operating angle Ï† can be acquired.

Additionally, when Eq(2) is differentiated by the angle {circumflex over (Î¸)}₁, the cosine function of the angle 2Î”Î¸1 can be acquired. The equation can be presented as follows:

$\begin{matrix} \frac{{df}_{Î”Î¸ î¢ž î¢ž 1}}{d î¢ž î¢ž {\hat{Î¸}}_{1}} = k î¢ž î¢ž \cos î¢ž î¢ž 2 î¢ž î¢ž {Î”Î¸}_{1} Â\cdot \frac{d î¢ (2 î¢ž î¢ž {Î”Î¸}_{1})}{d î¢ž î¢ž {\hat{Î¸}}_{1}} = k î¢ž î¢ž \cos î¢ž î¢ž 2 î¢ž î¢ž {Î”Î¸}_{1} Â\cdot (- 2) & Eq î¢ž î¢ž (3) \end{matrix}$

To solve the equation above, the high frequency signal injection module 110 injects a second high frequency signal f₁₂with a value U_icos Ï‰_it to the d-axis of the motor 10 at the second estimating angle {circumflex over (Î¸)}₂. The sensing module 120 senses the stator currents i_U2, i_V2, i_W2, on the motor 10, and accordingly generates the response current Ã®_d2, on the d-axis of the motor 10 and the response current Ã®_q2on the q-axis of the motor 10. Subsequently, the calculating module 130 samples the response current Ã®_q2and mixes (or multiplies) the response current Ã®_q2with the high frequency carrier f, having the value sin, wt to generate a second mixing signal m2. Subsequently, the calculating module 130 low-pass filters the second mixing signal m2 to acquire a second calculating value f_Î”Î¸2. In a state where there is a tiny difference between the first estimating angle {circumflex over (Î¸)}₁and the second estimating angle {circumflex over (0)}₂(e.g., {circumflex over (Î¸)}₂âˆ’{circumflex over (Î¸)}₁=dÎ¸), Eq(3) presented above can be solved by the first estimating angle {circumflex over (Î¸)}₁, the second estimating angle {circumflex over (Î¸)}₂, the first calculating value f_Î”Î¸1, and the second calculating value f_Î”Î¸2, such that the value of the cosine function of the angle 2Î”Î¸1 (that is, the cosine function of the operating angle Ï†) can be acquired. The equation can be presented as follows:

$\begin{matrix} \frac{f_{Î”Î¸ î¢ž î¢ž 2} - f_{Î”Î¸ î¢ž î¢ž 1}}{{\hat{Î¸}}_{2} - {\hat{Î¸}}_{1}} = \frac{{df}_{Î”Î¸ î¢ž î¢ž 1}}{d î¢ž î¢ž {\hat{Î¸}}_{1}} = k î¢ž î¢ž \cos î¢ž î¢ž 2 î¢ž î¢ž {Î”Î¸}_{1} Â\cdot \frac{d î¢ (2 î¢ž î¢ž {Î”Î¸}_{1})}{d î¢ž î¢ž {\hat{Î¸}}_{1}} = k î¢ž î¢ž \cos î¢ž î¢ž 2 î¢ž {Î”Î¸}_{1} Â\cdot (- 2) & Eq î¢ž î¢ž (4) \end{matrix}$

After the values of the sine function and the cosine function of the angle 2Î”Î¸1 are acquired, the calculating module 130 determines the quadrant of the angle 2Î”Î¸1 accordingly. For example, when both of the values of k sin 2Î”Î¸₁and k cos 2Î”Î¸₁are positive numbers, the angle 2Î”Î¸1 is in the first quadrant. When the value of k sin 2Î”Î¸₁is a positive number, and the value of k cos 2Î”Î¸₁is a negative number, the angle 2Î”Î¸1 is in the second quadrant.

Additionally, after the values of the sine function and the cosine function of the angle 2Î”Î¸1 are acquired, the calculating module 130 calculates the angle difference Î”Î¸₁between the first estimating angle {circumflex over (Î¸)}₁and the rotor position Î¸ through the inverse trigonometric function. The equation can be presented as follows:

$\begin{matrix} 2 î¢ž î¢ž {Î”Î¸}_{1} = \tan^{- 1} î¢ž î¢ž (f_{Î”Î¸ î¢ž î¢ž 1} Ã\cdot (\frac{{df}_{Î”Î¸ î¢ž î¢ž 1}}{d î¢ž î¢ž {\hat{Î¸}}_{1}}) Ã— (- 2)) & Eq î¢ž î¢ž (5) \end{matrix}$

Through such operation, the calculating module 130 can calculate the rotor position Î¸ according to the angle difference Î”Î¸₁between the first estimating angle {circumflex over (Î¸)}₁and the rotor position Î¸ (since Î”Î¸₁=Î¸={circumflex over (Î¸)}₁, and both of Î”Î¸₁and {circumflex over (Î¸)}₁are known).

It should be noted that although the first high frequency signal f₁₁and the second high frequency signal f₁₂are injected to the d-axis of the motor 10, and the calculating module 130 samples the response currents Ã®_q1, Ã®_q2on the q-axis of the motor 10, so as to generate the first calculating value f_Î”Î¸1and the second calculating value f_Î”Î¸2in the exemplary embodiment above, the invention is not limited by such operation.

In one embodiment, in the period when a high frequency signal with a value U₁cos Ï‰_it is injected to the q-axis of the motor 10, the response currents Ã®_d, Ã®_qrespectively on the d-axis and q-axis can be presented as follows:

$\begin{matrix} [\begin{matrix} {\hat{i}}_{d î¢ž} \\ {\hat{i}}_{q î¢ž} \end{matrix}] = [\begin{matrix} \frac{- U_{i} î¢ž î¢ž \sin î¢ž î¢ž {Ï‰}_{i} î¢ž t}{{Ï‰}_{i} î¢ (L^{2} - Î” î¢ž î¢ž L^{2})} î¢ž Î” î¢ž î¢ž L î¢ž î¢ž \sin î¢ž î¢ž 2 î¢ž î¢ž Î”Î¸ \\ \frac{U_{i} î¢ž î¢ž \sin î¢ž î¢ž {Ï‰}_{i} î¢ž t}{{Ï‰}_{i} î¢ (L^{2} - Î” î¢ž î¢ž L^{2})} î¢ž (L + Î” î¢ž î¢ž L î¢ž î¢ž \cos î¢ž î¢ž 2 î¢ž î¢ž Î”Î¸) î¢ž \end{matrix}] & Eq î¢ž î¢ž (6) \end{matrix}$

In the equation above, Î”Î¸=Î¸âˆ’{circumflex over (Î¸)}.

In this embodiment, the calculating module 130 can sample the response current Ã®_don the d-axis of the motor 10, mix the response current Ã®_dwith the high frequency carrier f_chaving the value sin Ï‰_it to generate a mixing signal, and low-pass filter the mixing signal to acquire a calculating value f_Î”Î¸=k sin 2Î”Î¸. Therefore, in this embodiment, through operations similar to those in the exemplary embodiment above, the values of the sine function and the cosine function of the angle 2Î”Î¸1 can be acquired, and the rotor position Î¸ can be accordingly calculated. A description in this regard will not be repeated herein.

In one embodiment, in the period when a high frequency signal with a value U_icos Ï‰_it is injected to the d-axis and the q-axis of the motor 10 at the same time, the response currents Ã®_d, Ã®_q, respectively on the d-axis and q-axis can be presented as follows:

$\begin{matrix} [\begin{matrix} {\hat{i}}_{d î¢ž} \\ {\hat{i}}_{q î¢ž} \end{matrix}] = [\begin{matrix} \frac{U_{i} î¢ž î¢ž \sin î¢ž î¢ž {Ï‰}_{i} î¢ž t}{{Ï‰}_{i} î¢ (L^{2} - Î” î¢ž î¢ž L^{2})} î¢ž (L - Î” î¢ž î¢ž L î¢ž î¢ž \cos î¢ž î¢ž 2 î¢ž î¢ž Î”Î¸ - Î” î¢ž î¢ž L î¢ž î¢ž \sin î¢ž î¢ž 2 î¢ž î¢ž Î”Î¸) \\ \frac{U_{i} î¢ž î¢ž \sin î¢ž î¢ž {Ï‰}_{i} î¢ž t}{{Ï‰}_{i} î¢ (L^{2} - Î” î¢ž î¢ž L^{2})} î¢ž (L + Î” î¢ž î¢ž L î¢ž î¢ž \cos î¢ž î¢ž 2 î¢ž î¢ž Î”Î¸ - Î” î¢ž î¢ž L î¢ž î¢ž \sin î¢ž î¢ž 2 î¢ž Î”Î¸) î¢ž \end{matrix}] & Eq î¢ž î¢ž (7) \end{matrix}$

In this embodiment, the calculating module 130 can sample the response current Ã®_don the d-axis of the motor 10, mix the response current Ã®_dwith the high frequency carrier f_chaving the value sin Ï‰_it to generate a mixing signal, and low-pass filter the mixing signal to acquire a calculating value f_Î”Î¸-d. In addition, the calculating module 130 can sample the response current Ã®_qon the q-axis of the motor 10, mix the response current Ã®_qwith the high frequency carrier f_chaving the value sin Ï‰_it to generate another mixing signal, and low-pass filter the another mixing signal to acquire a calculating value f_Î”Î¸-q, The calculating values f_Î”Î¸-d, f_Î”Î¸-qcan be presented as follows:

$\begin{matrix} [\begin{matrix} f_{Î”Î¸ - d} \\ f_{Î”Î¸ - q} \end{matrix}] = [\begin{matrix} \frac{U_{i}}{2 î¢ž î¢ž {Ï‰}_{i} î¢ (L^{2} - Î” î¢ž î¢ž L^{2})} î¢ž (L - Î” î¢ž î¢ž L î¢ž î¢ž \cos î¢ž î¢ž 2 î¢ž î¢ž Î”Î¸ - Î” î¢ž î¢ž L î¢ž î¢ž \sin î¢ž î¢ž 2 î¢ž î¢ž Î”Î¸) \\ \frac{U_{i}}{2 î¢ž î¢ž {Ï‰}_{i} î¢ (L^{2} - Î” î¢ž î¢ž L^{2})} î¢ž (L + Î” î¢ž î¢ž L î¢ž î¢ž \cos î¢ž î¢ž 2 î¢ž î¢ž Î”Î¸ - Î” î¢ž î¢ž L î¢ž î¢ž \sin î¢ž î¢ž 2 î¢ž î¢ž Î” î¢ž î¢ž Î¸) \end{matrix}] & Eq î¢ž î¢ž (8) \end{matrix}$

An equation Eq(9) can be derived using equation Eq(8). The equation Eq(9) is presented as follows:

$\begin{matrix} [\begin{matrix} f_{Î”Î¸ - q} - f_{Î”Î¸ - d} \\ \frac{{df}_{Î”Î¸ - d}}{d î¢ž î¢ž \hat{Î¸}} - \frac{{df}_{Î”Î¸ - q}}{d î¢ž î¢ž \hat{Î¸}} \end{matrix}] = [\begin{matrix} \frac{U_{i î¢ž}}{2 î¢ž î¢ž {Ï‰}_{i} î¢ (L^{2} - Î” î¢ž î¢ž L^{2})} î¢ž (2 î¢ž î¢ž Î” î¢ž î¢ž L î¢ž î¢ž \cos î¢ž î¢ž 2 î¢ž î¢ž Î”Î¸) \\ \frac{U_{i}}{2 î¢ž î¢ž {Ï‰}_{i} î¢ (L^{2} - Î” î¢ž î¢ž L^{2})} î¢ž (2 î¢ž î¢ž Î” î¢ž î¢ž L î¢ž î¢ž \sin î¢ž î¢ž 2 î¢ž î¢ž Î”Î¸) Â\cdot (- 2) \end{matrix}] & Eq î¢ž î¢ž (9) \end{matrix}$

Therefore, in this embodiment, through operations similar to those in the exemplary embodiment above, the values of the sine function and the cosine function of the angle 2Î”Î¸1 can be acquired using Eq(9), and the rotor position Î¸ can be accordingly calculated. A description in this regard will not be repeated herein.

Through such operation, by providing the first high frequency signal f₁₁and the second high frequency signal f₁₂to the motor 10 at the first estimating angle {circumflex over (Î¸)}₁and the second estimating angle {circumflex over (Î¸)}₂respectively, the estimating device 100 can rapidly determine the quadrant of the operating angle Ï†, so as to rapidly calculate the value of the operating angle Ï† to acquire the rotor position Î¸. Through application of the estimating device 100, the control of the motor 10 can be more stable.

In the following paragraphs, more details of the high frequency signal injection module 110, the sensing module 120, and the calculating module 130 are provided. However, the invention is not limited by the embodiments below.

As mentioned above, the high frequency signal injection module 110 is configured to inject the first high frequency signal f₁₁to the motor 10 at the first estimating angle {circumflex over (Î¸)}₁through the inverter 20, and inject the second high frequency signal f₁₂to the motor 10 at the second estimating angle {circumflex over (Î¸)}₂through the inverter 20.

To achieve such a function, in this embodiment, the high frequency signal injection module 110 includes an injection signal generating unit 112, an adder A1, an inverse Park transformation unit 114, and a pulse width modulation (PWM) signal generating unit 116 (e.g., a space vector pulse width modulation (SVPWM) signal generating unit). The injection signal generating unit 112 is electrically connected to a q-axis input end of the inverse Park transformation unit 114 and the adder A1. The adder A1 is electrically connected to a d-axis input end of the inverse Park transformation unit 114. The inverse Park transformation unit 114 is electrically connected to the PWM signal generating unit 116. The PWM signal generating unit 116 is electrically connected to the inverter 20.

The injection signal generating unit 112 is configured to separately generate the first high frequency signal f₁₁and the second high frequency signal f₁₂, a d-axis reference signal {circumflex over (v)}_d,ref, a q-axis reference signal {circumflex over (v)}_q,ref, the first estimating angle {circumflex over (Î¸)}₁, and the second estimating angle {circumflex over (Î¸)}₂. Both of the values of the first high frequency signal f₁₁and the second high frequency signal f₁₂are, for example, U_icos Ï‰_it. Both of the values of the d-axis reference signal {circumflex over (v)}_d,refand the q-axis reference signal {circumflex over (v)}_q,refare, for example, zero. The value of the first estimating angle {circumflex over (Î¸)}₁is, for example, zero. The value of the second estimating angle {circumflex over (Î¸)}₂is, for example, d{circumflex over (Î¸)}₁. Additionally, both of the first high frequency signal f₁₁and the second high frequency signal f₁₂are voltage signals.

The adder A1 is configured to receive the first high frequency signal f₁₁, the second high frequency signal f₁₂, and the d-axis reference signal {circumflex over (v)}_d,ref, separately add the first high frequency signal f₁₁with the d-axis reference signal {circumflex over (v)}_d,refand the second high frequency signal f₁₂with the d-axis reference signal {circumflex over (v)}_d,ref, and transmit the added signals to the d-axis input end of the inverse Park transformation unit 114.

In a period when receiving the first estimating angle {circumflex over (Î¸)}₁, the inverse Park transformation unit 114 is configured to generate first converting signals v_Î±1, v_Î²1according to the first estimating angle {circumflex over (Î¸)}₁, the first high frequency signal f₁₁, the d-axis reference signal {circumflex over (v)}_d,ref, and the q-axis reference signal {circumflex over (v)}_q,ref. Additionally, in a period when receiving the second estimating angle {circumflex over (Î¸)}₂, the inverse Park transformation unit 114 is configured to generate second converting signals v_Î±2, v_Î²2according to the second estimating angle {circumflex over (Î¸)}₂, the second high frequency signal f₁₂, the d-axis reference signal {circumflex over (v)}_d,ref, and the q-axis reference signal {circumflex over (v)}_q,ref.

When receiving the first converting signal v_Î±1, v_Î²1(e.g., in the period when the inverse Park transformation unit 114 receives the first estimating angle {circumflex over (Î¸)}₁), the PWM signal generating unit 116 is configured to provide first SVPWM signals v_Î±1c, v_Î²1ccorresponding to the first frequency signal f₁₁to the inverter 20. When receiving the second converting signal v_Î±2, v_Î²2(e.g., in the period when the inverse Park transformation unit 114 receives the second estimating angle {circumflex over (Î¸)}₂), the PWM signal generating unit 116 is configured to provide second SVPWM signals v_Î±2c, v_Î²2ccorresponding to the second frequency signal f₁₂to the inverter 20.

Through such a configuration, the high frequency signal injection module 110 can inject the first high frequency signal f₁₁to the motor 10 at the first estimating angle {circumflex over (Î¸)}₁through the inverter 20, and inject the second high frequency signal f₁₂to the motor 10 at the second estimating angle {circumflex over (Î¸)}₂through the inverter 20.

It should be noted that, in the embodiment above, since the adder A1 is electrically connected to the d-axis input end of the inverse Park transformation unit 114, the first high frequency signal f₁₁and the second high frequency signal f₁₂are injected to the d-axis of the motor 10. However, as mentioned in the paragraphs above, the first high frequency signal f₁₁and the second high frequency signal f₁₂can be injected to the q-axis of the motor 10, or injected to the d-axis and q-axis of the motor 10. Thus, the invention is not limited by the embodiment described above.

As mentioned above, the sensing module 120 is configured to sense the stator currents i_U1, i_V1, i_W1, i_U2, i_V2, i_W2on the motor 10, and accordingly generate the response currents Ã®_q1, Ã®_q2on the d-axis of the motor 10 and the response currents Ã®_q1, Ã®_q2on the q-axis of the motor 10. The first sensing signal is at least one of the response currents Ã®_d1, Ã®_q1, and the second sensing signal is at least one of the response currents Ã®_d2, Ã®_q2.

In this embodiment, the sensing module 120 includes a Clarke transformation unit 122 and a Park transformation unit 124. The Clarke transformation unit 122 and the Park transformation unit 124 are electrically connected to each other.

The Clarke transformation unit 122 is configured to receive the stator currents i_U1, i_V1, i_W1of the motor 10, and generate converting signals i_Î±1, i_Î²1according to the stator currents i_U1, i_V1, i_W1. Additionally, the Clarke transformation unit 122 is configured to receive the stator currents i_U2, i_V2, i_W2of the motor 10, and generate converting signals i_Î±2, i_Î²2according to the stator currents i_U2, i_V2, i_W2.

The Park transformation unit 124 is configured to receive the converting signals i_Î±1, i_Î²1, and generate response currents Ã®_d1, Ã®_q1, according to the converting signals i_Î±1, i_Î²1. Additionally, the Park transformation unit 124 is configured to receive the converting signals i_Î±2, i_Î²2, and generate response currents Ã®_d2, Ã®_q2according to the converting signals i_Î±2, i_Î²2.

Through such a configuration, in the period when the high frequency signal injection module 110 injects the first high frequency signal f₁₁to the motor 10, the sensing module 120 can accordingly generate the response current Ã®_d1on the d-axis of the motor 10 and the response currents Ã®_q1on the q-axis of the motor 10. Additionally, in the period when the high frequency signal injection module 110 injects the second high frequency signal f₁₂to the motor 10, the sensing module 120 can accordingly generate the response current Ã®_d2on the d-axis of the motor 10 and the response currents Ã®_q2on the q-axis of the motor 10.

As mentioned above, the calculating module 130 is configured to calculate the operating angle Ï† and the rotor position Î¸ according to the first sensing signal (e.g., at least one of response currents Ã®_d2, Ã®_q2) and the second sensing signal (e.g., at least one of response currents Ã®_d2, Ã®_q2).

In this embodiment, the calculating module 130 includes a mixer M1, a filtering unit 132, a first calculating unit 134, a quadrant determining unit 136, a second calculating unit 138, a mixer M2, and an adder A2. The mixer M1 is electrically connected to a q-axis output end of the Park transformation unit 124 and the filtering unit 132. The filtering unit 132 is electrically connected to the first calculating unit 134 and the quadrant determining unit 136. The first calculating unit 134 is electrically connected to the quadrant determining unit 136. The quadrant determining unit 136 is electrically connected to the second calculating unit 138. The second calculating unit 138 is electrically connected to the mixer M2. The mixer M2 is electrically connected to the adder A2.

In this embodiment, the mixer M1 is configured to receive the response current Ã®_q1(e.g., the first sensing signal in this embodiment) and the response current Ã®_q2(e.g., the second sensing signal in this embodiment) from the q-axis output end of the Park transformation unit 124. Additionally, the mixer M1 is configured to receive the high frequency carrier f_c(e.g., the high frequency carrier f_chas a value sin Ï‰_it). The mixer M1 is configured to mix the first sensing signal Ã®_q1with the high frequency carrier f_cto generate the first mixing signal m1, and mix the second sensing signal Ã®_q2with the high frequency carrier f_cto generate the second mixing signal m2.

The filtering unit 132 is configured to sequentially receive the first mixing signal m1 and the second mixing signal m2, and sequentially low-pass filter the first mixing signal m1 and the second mixing signal m2 to respectively generate the first calculating value f_Î”Î¸1and the second calculating value f_Î”Î¸2. The value of the sine function of the operating angle Ï† can be acquired according to the first calculating value f_Î”Î¸1.

The first calculating unit 134 is configured to acquire the value of the cosine function of the operating angle Ï† according to the first calculating value f_Î”Î¸1, the second calculating value f_Î”Î¸2, the first estimating angle {circumflex over (Î¸)}₁and the second estimating angle {circumflex over (Î¸)}₂.

Subsequently, the quadrant determining unit 136 is configured to determine the quadrant of the operating angle Ï† according to the values of the sine function and the cosine function of the operating angle Î¸.

The second calculating unit 138 is configured to calculate the value of the operating angle Ï† through the inverse trigonometric function according to the values of the sine function and the cosine function of the operating angle Ï†.

Subsequently, the mixer M2 is configured to generate the angle difference Î”Î¸₁between the first estimating angle {circumflex over (Î¸)}₁and the rotor position Î¸ according to the operating angle Ï†.

Next, the adder A2 is configured to generate the rotor position Î¸ according to the angle difference Î”Î¸₁between the first estimating angle {circumflex over (Î¸)}₁and the rotor position Î¸.

It should be noted that details of the units in this embodiment can be ascertained by referring to the exemplary embodiment mentioned above, and a description in this regard will not be repeated herein.

Through such a configuration, the calculating module 130 can calculate the operating angle Ï† and the rotor position Î¸ according to the first sensing signal (e.g., response current Ã®_q1) and the second sensing signal (e.g., response current Ã®_q2).

In addition, since the mixer M1 samples the response currents Ã®_q1, Ã®_q2on the q-axis output end of the Park transformation unit 124, in the embodiment above, the response current Ã®_q1serves as the first sensing signal, the response current Ã®_q2serves as the second sensing signal, and the calculating module 130 calculates the operating angle Ï† and the rotor position Î¸ according to the response currents Ã®_q1, Ã®_q2. However, as mentioned above, the calculating module 130 can sample the response currents Ã®_d1, Ã®_d2on the d-axis output end of the Park transformation unit 124, or sample the response currents Ã®_d1, Ã®_d2, Ã®_q1, Ã®_q2on the d-axis output end and the q-axis output end of the Park transformation unit 124. That is, in some embodiments, the response currents Ã®_d1, Ã®_d2can serve as the first sensing signal and the second sensing signal respectively, or the response currents Ã®_d1, Ã®_q1and Ã®_d2, Ã®_q2can serve as the first sensing signal and the second sensing signal respectively. The invention is not limited in this regard by the embodiment described above.

Another aspect of the present invention is an estimating method for a rotor position of a motor.

The estimating method can be applied to an estimating device having a structure that is the same as or similar to the structure shown in FIG. 1 and FIG. 2. To simplify the description below, in the following paragraphs, the embodiments shown in FIG. 1 and FIG. 2 will be used as an example to describe the estimating method according to embodiments of the present disclosure. However, the invention is not limited to application to the embodiments shown in FIG. 1 and FIG. 2.

In addition, it should be noted that, in the steps of the following estimating method, no particular sequence is required unless otherwise specified. Moreover, the following steps also may be performed simultaneously or the execution times thereof may at least partially overlap.

FIG. 3 is a flow chart of an estimating method 300 in accordance with one embodiment of the present disclosure. The estimating method 300 includes the steps below.

In step S1, through the high frequency signal injection module 110 and the inverter 20, the first high frequency signal f₁₁is injected to the motor 10 at the first estimating angle {circumflex over (Î¸)}₁.

In step S2, through the sensing module 120, in the period when the first high frequency signal f₁₁is injected to the motor 10, the stator currents i_U1, i_V1, i_W1, of the motor 10 are sensed, and the first sensing signal of the motor 10 is generated according to the stator currents i_U1, i_V1, i_W1.

In step S3, through the high frequency signal injection module 110 and the inverter 20, the second high frequency signal f₁₂is injected to the motor 10 at the second estimating angle {circumflex over (Î¸)}₂. The second estimating angle {circumflex over (Î¸)}₂is different from the first estimating angle {circumflex over (Î¸)}₁.

In step S4, through the sensing module 120, in the period when the second high frequency signal f₁₂is injected to the motor 10, the stator currents i_U2, i_V2, i_W2of the motor 10 are sensed, and the second sensing signal of the motor 10 is generated according to the stator currents i_U2, i_V2, i_W2.

In step S5, through the calculating module 130, the values of the sine function and the cosine function of the operating angle Ï† are acquired, and the quadrant of the operating angle Ï† is determined according to whether each of the values of the sine function and the cosine function of the operating angle Ï† is a positive number or a negative number. The operating angle Ï† corresponds to the angle difference Î”Î¸₁between the first estimating angle {circumflex over (Î¸)}₁and the rotor position Î¸ (e.g., Î”Î¸₁=Î¸âˆ’{circumflex over (Î¸)}₁). In one embodiment, the operating angle Ï† is twice as large as the angle difference Î”Î¸₁between the first estimating angle {circumflex over (Î¸)}₁and the rotor position Î¸ (e.g., Ï†=2Ã—Î”Î¸1).

In step S6, through the calculating module 130, the value of the operating angle Ï† is calculated through the inverse trigonometric function according to the values of the sine function and the cosine function of the operating angle Ï†. Subsequently, the calculating module 130 calculates the rotor position Î¸ according to the operating angle Ï†, the quadrant of the operating angle Ï†, and the first estimating angle Ï†.

In step S7, through the determining module 140, the direction of the magnetic north pole of the rotor of the motor 10 is determined using the pulse injection method. Hence, the rotor position Î¸ of the motor 10 can be ascertained.

Through such operation, by providing the first high frequency signal f₁₁and the second high frequency signal f₁₂to the motor 10 at the first estimating angle {circumflex over (Î¸)}₁and the second estimating angle {circumflex over (Î¸)}₂respectively, the estimating device 100 can rapidly determine the quadrant of the operating angle Ï†, so as to rapidly calculate the value of the operating angle Ï† to acquire the value of the rotor position Î¸. Through application of the estimating device 100, the control of the motor 10 can be more stable.

In accordance with one embodiment, the first sensing signal is at least one of the response current Ã®_d1on the d-axis of the motor 10 and the response current Ã®_q1on the q-axis of the motor 10. The second sensing signal is at least one of the response current Ã®_d2on the d-axis of the motor 10 and the response current Ã®_q2on the q-axis of the motor 10.

In accordance with one embodiment, in step S1, the high frequency signal injection module 110 injects the first high frequency signal f₁₁to at least one of the d-axis and the q-axis of the motor 10 at the first estimating angle {circumflex over (Î¸)}₁.

In accordance with one embodiment, in step S3, the high frequency signal injection module 110 injects the second high frequency signal f₁₂to at least one of the d-axis and the q-axis of the motor 10 at the second estimating angle {circumflex over (Î¸)}₂. The first high frequency signal f₁₁and the second high frequency signal f₁₂are injected to the same q-axis of the motor 10, the same d-axis of the motor 10, or both of the q-axis and the d-axis of the motor 10.

In accordance with one embodiment, in step S5, the calculating module 130 mixes the first sensing signal with the high frequency carrier f_cto generate the first mixing signal m1, and low-pass filters the first mixing signal m1 to acquire a first calculating value f_Î”Î¸1. The calculating module 130 acquires the value of the sine function of the operating angle Ï† according to the first calculating value f_Î”Î¸1.

Additionally, in accordance with one embodiment, in step S5, the calculating module 130 mixes the second sensing signal with the high frequency carrier f_cto generate the second mixing signal m2, and low-pass filters the second mixing signal m2 to acquire a second calculating value f_Î”Î¸2. Subsequently, the calculating module 130 acquires the value of the cosine function of the operating angle according to the first calculating value f_Î”Î¸1, the second calculating value f_Î”Î¸2, the first estimating angle, and the second estimating angle {circumflex over (Î¸)}₂.

Moreover, in accordance with one embodiment, in step S5, the calculating module 130 calculates the value of the operating angle Ï† through an inverse trigonometric function according to the values of the sine function and the cosine function of the operating angle Ï†. Subsequently, the calculating module 130 calculates the value of the rotor position Î¸ according to the operating angle Ï†, the quadrant of the operating angle Ï†, and the first estimating angle {circumflex over (Î¸)}₁.

It should be noted that details of steps S1-S7 can be ascertained by referring to the exemplary embodiment mentioned above, and a description in this regard will not be repeated herein.

It will be apparent to those skilled in the art that various modifications and variations can be made to the structure of the present invention without departing from the scope or spirit of the invention. In view of the foregoing, it is intended that the present invention cover modifications and variations of this invention provided they fall within the scope of the following claims.