KR102542636B1 - Correcting device for resolver offset of inverter and correction method thereof - Google Patents

Abstract

The present invention relates to an apparatus and method for compensating a resolver offset of an inverter, which performs current control for forcibly aligning a rotor with respect to each of the first and second phases of a motor when power is supplied, and the received first and second phases. An MCU that calculates the number of poles of the resolver using the resolver absolute angle for the second phase, a resolver that detects rotor position information of the motor in which the rotor is aligned by current control of the MCU, and the resolver and an R/D converter that converts the detected rotor position information into a digital signal and provides the absolute resolver angle for each of the first and second phases to the MCU.

Description

Resolver offset correction device and method of inverter {Correcting device for resolver offset of inverter and correction method thereof}

The present invention relates to an apparatus and method for compensating a resolver offset of an inverter, and more particularly, to an apparatus and method capable of automatically detecting the number of resolver poles and an offset and automatically correcting them in an inverter.

In general, factories or buildings use AC motors for various purposes, such as driving a fan of an air conditioning system and driving a pump. In factories and buildings, three-phase induction motors or permanent magnet synchronous motors are mainly used as AC motors. The above motors use a position sensor to detect rotor position information and apply the detected rotor position information and vector control theory to low speed including zero speed compared to sensorless operation or output voltage/frequency (V/F) operation. High-performance control is possible in

As the position sensor, an encoder and a resolver are usually used, but a resolver that is more resistant to dust or impact than the encoder and does not easily fail is mainly used.

A resolver is a device that receives an AC voltage and outputs an AC signal including position information of a rotor, and is also used to control a motor of an electric vehicle.

Usually, the resolver is mounted on the rear plate of the motor and detects the position and speed information of the rotor.

When mounting the resolver on the motor, it is necessary to mount it in an accurate position so that no correction is required, but it is not easy to mount it in an accurate position due to mechanical assembly tolerances.

This difference in position causes a difference between the position of the motor rotor and the rotor position information output from the resolver, and this difference is called an offset.

Therefore, the offset correction method for correcting the output of the resolver and the phase of the motor rotor to be the same is required.

The structure of the resolver itself is similar to that of a motor having a stator and a rotor, and the stator uses one-phase excitation winding and two-phase detection winding. The shape of the iron core of the rotor changes according to the rotation angle so that the amount of flux linkage fluctuates.

In this structure, a high-frequency excitation signal is applied to the excitation winding, and the reluctance is changed while the rotor rotates, so that the primary and secondary side mutual flux linkages are periodically changed.

The output voltage amplitude of the two-phase detection winding of the stator changes in proportion to the rotation angle, and this analog value is changed to the position angle through RDC (Resolver to Digital Converter).

Normally, the resolver must be combined with a product with the same number of poles as the number of poles of the motor, but a resolver with a different number of poles from the number of poles of the motor can be applied to each product, especially when controlling an existing motor rather than a new installation. is often difficult to know.

Regarding the method of correcting the offset of the resolver, as in the method presented in Registered Patent No. 10-1597440 (Resolver Offset Correction Method, registered on February 18, 2016), based on whether the motor rotates, using the motor current Methods of calculating a resolver offset and performing correction by reflecting the calculated offset have been proposed.

However, these methods are difficult to apply when the number of poles of the resolver is unknown because the formula is complicated and can be applied when the number of poles of the resolver is known.

An object to be solved by the present invention in consideration of the above problems is to provide an apparatus and method capable of detecting and correcting an offset even when the number of poles of a resolver is unknown.

In addition, another problem to be solved by the present invention is to provide an apparatus and method capable of simplifying an offset detection formula.

An inverter resolver offset correction device according to an aspect of the present invention for solving the above technical problem is a current control for forcibly aligning a rotor with respect to each of the first and second phases of a motor when power is supplied. At the same time, an MCU that calculates the number of poles of the resolver using the received absolute angles of the resolver for the first and second phases, and the rotor position information of the motor in which the rotor is aligned by current control of the MCU is detected. And a resolver that converts the rotor position information detected by the resolver into a digital signal and provides an absolute resolver angle for each of the first and second phases to the MCU. The MCU may calculate the resolver pole number using Equation 1 below.

[Equation 1]

n = (2nd phase rotor electrical angle - 1st phase rotor electrical angle) / (2nd phase resolver absolute angle - 1st phase resolver absolute angle)

n is the ratio of the number of poles of the motor to the number of poles of the resolver

In an embodiment of the present invention, the R/D converter may provide the first resolver absolute angle and the second resolver absolute angle to the MCU as an A/B pulse that is an incremental signal.

In an embodiment of the present invention, the R/D converter may provide the first resolver absolute angle and the second resolver absolute angle to the MCU through serial or parallel communication.

In an embodiment of the present invention, the first phase is U phase, -U phase, V phase, -V phase, W phase, or -W phase, and may be preferably U phase or -U phase for simplifying the formula.

In an embodiment of the present invention, the second phase is a phase different from the first phase, and may preferably be a V phase or -V phase.

In addition, a resolver offset correction method of an inverter according to another aspect of the present invention includes the steps of a) forcibly aligning a motor rotor with respect to a first phase under the control of an MCU, and b) having the motor rotor in the first phase detecting the absolute angle of the rotor using a resolver in a state of forced alignment with respect to the first phase; c) forcibly aligning the motor rotor with respect to a second phase different from the first phase; d) Detecting the absolute angle of the rotor in the resolver in a state of forced alignment with respect to the second phase; e) the absolute angles of the resolver detected in steps b) and d), respectively, and It may include a step of calculating through Equation 1 below using the electrical angle of the first phase and the electrical angle of the second phase, respectively detected in step c).

[Equation 1]

n = (2nd phase rotor electrical angle - 1st phase rotor electrical angle) / (2nd phase resolver absolute angle - 1st phase resolver absolute angle)

n is the ratio of the number of poles of the motor to the number of poles of the resolver

In an embodiment of the present invention, the absolute angle of the resolver of the first phase and the absolute angle of the resolver of the second phase may be an output of an R/D converter that converts an analog output of the resolver into a digital signal.

In an embodiment of the present invention, the absolute angle of the resolver of the first phase and the absolute angle of the resolver of the second phase may be provided to the MCU as an A/B pulse, which is an incremental signal of the R/D converter.

In an embodiment of the present invention, the absolute angle of the resolver of the first phase and the absolute angle of the resolver of the second phase may be provided to the MCU through serial or parallel communication in the R/D converter.

The present invention calculates the number of poles of the resolver using the output angle of the resolver, thereby detecting the offset between the resolver whose pole number is unknown and the motor whose pole number is known. There is a corrective effect.

In addition, the present invention has an effect of enabling more accurate correction by simplifying a complicated formula by using the absolute angle of the resolver for calculating and correcting the offset.

1 is a block diagram of a resolver offset correction device of an inverter according to a preferred embodiment of the present invention.
2 is a graph comparing the absolute angle of the resolver and the electrical angle of the rotor.
3 is a graph showing the relationship between the absolute angle of the resolver and the electrical angle of the rotor when n is 2.
4 is a graph showing the relationship between the absolute angle of the resolver and the electrical angle of the rotor when n is 0.5.
5 is a flowchart showing a method for correcting a resolver offset of an inverter according to the present invention.

In order to fully understand the configuration and effects of the present invention, preferred embodiments of the present invention will be described with reference to the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, and may be implemented in various forms and various changes may be made. However, the description of the present embodiment is provided to complete the disclosure of the present invention and to completely inform those skilled in the art of the scope of the invention to which the present invention belongs. In the accompanying drawings, the size of the components is enlarged from the actual size for convenience of description, and the ratio of each component may be exaggerated or reduced.

Terms such as 'first' and 'second' may be used to describe various elements, but the elements should not be limited by the above terms. The above terms may only be used for the purpose of distinguishing one component from another. For example, without departing from the scope of the present invention, a 'first element' may be named a 'second element', and similarly, a 'second element' may also be named a 'first element'. can Also, singular expressions include plural expressions unless the context clearly indicates otherwise. Terms used in the embodiments of the present invention may be interpreted as meanings commonly known to those skilled in the art unless otherwise defined.

Hereinafter, an apparatus and method for compensating a resolver offset of an inverter according to an embodiment of the present invention will be described in detail with reference to the drawings.

1 is a block diagram of a resolver offset correction device of an inverter according to a preferred embodiment of the present invention.

Referring to FIG. 1, the present invention receives the detection signal of the resolver 20 for detecting the position of the rotor of the motor 10, converts it into a digital signal, and outputs the resolver digital converter (R/D Converter, hereinafter R). /D converter, 30) and a microcontroller unit (hereinafter, abbreviated as MCU) that receives the output signal of the R/D converter 30, receives the driving current of the motor 10 as feedback, and outputs a driving command 40), a gate driving unit 50 outputting a gate driving signal according to the driving command of the MCU 40, a rectifying unit 70 rectifying the AC power supply 60, and the voltage of the rectifying unit 70 It includes a smoothing unit 80 for smoothing and an inverter unit 90 for supplying current to each phase of the motor 10 according to the gate driving signal of the gate driving unit 50.

In particular, when the number of poles of the resolver 20 is not known, the MCU 40 of the present invention outputs a command to forcibly align the position of the rotor of the motor 10 sequentially with respect to two different phases. do.

More specifically, the MCU 40 controls the gate driver 50 to perform control such that current flows only through the inverter unit 90 to the U phase (which may be indicated as R, A or X phase). The rotor of the electric motor 10 is forcibly aligned to the U phase.

At this time, the output signal of the resolver 20 that detects the position of the rotor of the motor 10 is input to the R/D converter 30.

In addition, the MCU 40 controls the gate driver 50 again so that current flows only through the inverter unit 90 to the V phase (which can be expressed as S, B or Y) that is 120 degrees different from the U phase. so that the rotor of the electric motor 10 is forcibly aligned with the V phase.

At this time, the position of the rotor of the motor 10 is detected through the resolver 20 and provided to the R/D converter 30.

As such, two equations can be obtained through forced alignment of the rotor of the motor 10 for two different phases.

[Equation 1]

0 degrees = n(θres1 + θoffset)

[Equation 2]

120 degrees = n(θres2 + θoffset)

As described above, Equation 1 is a state equation in which the rotor of the motor 10 is forcibly aligned in the U-phase under the control of the MCU 40, and at this time, the mechanical position of the rotor of the motor 10 is assumed to be 0 degrees.

In Equation 1 above, θres1 is the angle of the rotor detected by the resolver 20 in the U-phase forced alignment state, and θoffset is the position of the rotor of the actual motor 10 and the rotor detected by the resolver 20. is the offset of the angle of

Also, n is the ratio of the number of poles of the motor 10 to the number of poles of the resolver 20.

Equation 2 is a state equation in which the rotor of the motor 10 is forcibly aligned to the V-phase position under the control of the MCU 40, and the mechanical position of the rotor of the motor 10 is 120 degrees.

θres2 is the angle of the rotor detected by the resolver 20 in a state where the rotor is forcibly aligned to the V-phase position.

The angle of the rotor detected by the resolver 20 is an analog signal that can be expressed as a sin or cos function, and is converted into a digital signal by the R/D converter 30.

Signals converted by the R/D converter 30 are provided to the MCU 40.

At this time, the output of the R/D converter 30 outputs an A/B pulse like a rotary encoder and transmits the resolver absolute angle to the MCU 40 through SPI (Serial Peripheral Interface) communication or parallel communication. there is.

The A/B pulse is an incremental signal, and an encoder usually displays a number of states by using the A-phase and B-phase signals to indicate mechanical movement. The number of states at this time is repeated.

To this end, the A-phase pulse and the B-phase pulse have a difference of 90 degrees, the movement amount can be known by counting the A-phase or B-phase pulses, and the movement direction can be confirmed from the phase relationship between the A-phase and B-phase.

The R/D converter 30 can output a set number of pulses per rotation of the resolver, and at this time, the generated pulses are provided to the MCU 40 to determine the movement amount and direction of the rotor detected by the resolver. It can be checked in the MCU 40.

The reason for setting the value of n is as follows.

2 is a graph comparing the absolute angle of the resolver and the electrical angle of the rotor.

The waveform of FIG. 2 shows the result converted to a digital signal in the aforementioned R/D converter 30, and the resolver 20 is a 4-pole and the motor 10 is an 8-pole example.

As in Equations 1 and 2 above, the electrical angle of the rotor can be calculated by adding an offset to the absolute angle of the resolver 20, but the resolver 20 is 4 poles and the motor 10 is 8 In the polar state, the value of n must be multiplied more to obtain an accurate mechanical angle.

3 is a graph showing the relationship between the absolute angle of the resolver and the electrical angle of the rotor when n is 2.

As shown here, when the absolute angle of the resolver is 0 degrees, the rotor electrical angle is 0 degrees, and even when the resolver absolute angle is 180 degrees, the rotor electrical angle is 0 degrees. The value of the rotor electrical angle can always be known.

This relationship can also be confirmed in the graph of FIG. 2 .

If n is 4, the rotor electrical angle becomes 0 degree when the resolver absolute angle is 0 degree, 90 degree, 180 degree, or 360 degree (same as 0 degree).

Therefore, in a state where the number of poles of the motor 10 is known, the number of poles of the resolver 20 can be known to know the rotor electrical angle for the detected absolute angle of the resolver.

If, as shown in FIG. 4, assuming that n is 0.5, since there are two values of the rotor electrical angle for the resolver electrical angle, it is impossible to determine which value it is.

In this way, in order to obtain the value of n, it is necessary to calculate the number of poles of the resolver.

Using Equation 1 above, it is possible to confirm the relationship between θ offset and θ res1.

It can be seen that n is a number other than 0, and the equation that θ offset is -θres1 is satisfied in order to satisfy Equation 1.

Substituting this into Equation 2, Equation 3 below can be obtained.

[Equation 3]

Equation 3 indicates that n is a value obtained by dividing 120 degrees, which is the V-phase position angle, by the difference between the two absolute angles (θres2, θres1) of the resolver 20.

In calculation, if the absolute value of θres1 is greater than the absolute value of θres2, n becomes a negative number, but this means that when the output of the inverter unit 90 is a positive sequence, the absolute angle of the resolver decreases, and the above-described R It only means that the B phase is ahead of the A phase at the output of the /D converter 30 by 90 degrees. If phase B leads phase A, it means that the direction of rotation is reversed.

The MCU 40 receives and knows the values of θres1 and θres2 in Equation 3 above through the A/B pulse of the R/D converter 30 or communication, and thus can calculate the value of n.

Assuming that the value of the absolute angle θres1 detected by the resolver 20 during the U-phase alignment is 35 and the value of the absolute angle θres2 detected by the resolver 20 during the V-phase alignment is 95, in Equation 3 above, n The value of becomes 2.

At this time, the offset (θ offset) is -35, and when the number of poles of the motor 10 is 4, the number of poles of the resolver 20 is 2.

Through this process, it is possible to check the number of poles of the resolver 20, which is an unknown number, and the offset value can be easily detected.

The MCU 40 corrects the offset using the pole number information and the offset of the resolver 20 detected in this way.

In the above examples, it has been described that the rotor of the motor 10 is forcibly aligned with respect to the U and V phases, but the rotor is forcibly aligned with respect to two different phases such as -U and W, and the resolver absolute at this time By detecting the angle, the number of poles and offset of the resolver 20 can be calculated.

In addition, since the present invention calculates the offset using the output of the R/D converter 30 without directly using the resolver output in the form of a trigonometric function, the formula can be simplified.

5 is a flowchart showing a method for correcting a resolver offset of an inverter according to the present invention.

Referring to FIG. 5, the resolver offset correction method of the inverter of the present invention includes the steps of forcibly aligning the rotor of the motor 10 with respect to the first phase (S51), and in the state in which the rotor is forcibly aligned with respect to the first phase, The step of confirming the absolute position of the rotor in the solver 20 (S52), the step of forcibly aligning the rotor of the motor 10 with respect to the second phase different from the first phase (S53), The step of confirming the absolute position of the rotor in the resolver 20 in the state of forcibly aligned with respect to the two phases (S54), and the absolute position value of the rotor of the resolver 20 confirmed in steps S52 and S54 and calculating the number of poles and offset of the resolver 20 by using (S55).

Looking at the method of the present invention in more detail, first, in step S51, the MCU 40 operates the gate driver 50 so that current selectively flows only in the specific first phase of the motor 10, such as the U phase or the -U phase. Control, and the inverter unit 90 supplies current to the first phase of the motor (10).

Therefore, the rotor of the motor 10 is forcibly arranged at the position of the first phase, and in step S52, the resolver 20 detects the angle of the fixed rotor and provides it to the R/D converter 30, and the R/D converter (30) converts the analog signal of the resolver 20 into a digital signal and provides it to the MCU 40 through A/B pulse or communication.

Next, as in step S53, the MCU 40 controls the gate driving unit 50 to selectively supply current only to the second phase different from the first phase, and the inverter unit 90 controls the power of the motor 10. By supplying current only to the second phase, the rotor is forcibly arranged in the second phase.

Then, as in step S54, the resolver 20 detects the angle of the rotor fixed at the position of the second phase and provides it to the R/D converter 30, and the R/D converter 30 detects the angle of the rotor fixed at the position of the second phase. The resolver absolute angle information for the rotor of is provided to the MCU 40.

Next, the MCU 40 obtains the value of n, which is the number of poles of the motor 10, relative to the number of poles of the resolver 20, using the two resolver absolute angles θres1 and θres2 identified in steps S52 and S53. offset can be obtained.

Specifically, an equation for obtaining the value of n may be expressed as Equation 4 below.

[Equation 4]

n = (2nd phase rotor electrical angle - 1st phase rotor electrical angle) / (2nd phase resolver absolute angle - 1st phase resolver absolute angle)

Equation 4 above is a generalization of Equations 1 to 3 described above.

More specifically, when the electrical angle of the rotor in the first phase is x1 and the electrical angle of the rotor in the second phase is x2, Equation 1 can be expressed as x1 = n (θres1 + θoffset), and solving this as an equation for θoffset θoffset = (x1/n) - θres1.

Substituting the electrical angle x2 of the rotor of the second phase into Equation 2, Equation 2 becomes x2 = n(θres2+θoffset).

If the θ offset obtained above is substituted for this, the expression x2 = n (θres2 + (x1/n) -θres1) is obtained.

Summarizing this for n, it can be expressed as n = (x2-x1)/θres2-θres1).

Here, n is the number of poles of the motor relative to the number of poles of the resolver, and if the number of poles of the motor is known, all other numbers are detectable constants, so the number of poles of the resolver can be confirmed.

Even if the number of poles of the motor is unknown, the number of poles of the motor relative to the number of poles of the resolver can be known, and this can be applied.

As such, the present invention uses a simple formula to easily know the number of poles of a resolver whose specifications are unknown.

Embodiments according to the present invention have been described above, but these are merely examples, and those skilled in the art will understand that various modifications and embodiments of equivalent range are possible therefrom. Therefore, the true technical protection scope of the present invention should be defined by the following claims.

10: motor 20: resolver
30: R/D converter 40: MCU
50: gate driving unit 90: inverter unit

Claims (9)

When power is supplied, current control is performed to forcibly align the rotor with respect to the first and second phases of the motor, and the number of poles of the resolver is used by using the received absolute angle of the resolver for the first and second phases. MCU that calculates ;
a resolver detecting rotor position information of an electric motor in which a rotor is aligned by current control of the MCU; and
An R/D converter converting the rotor position information detected by the resolver into a digital signal and providing the absolute angle of the resolver for each of the first and second phases to the MCU,
The MCU resolver offset correction device of the inverter for calculating the number of resolver poles using Equation 1 below.
[Equation 1]
n = (2nd phase rotor electrical angle - 1st phase rotor electrical angle) / (2nd phase resolver absolute angle - 1st phase resolver absolute angle)
n is the ratio of the number of poles of the motor to the number of poles of the resolver According to claim 1,
The R/D converter,
A resolver offset correction device of an inverter that provides the absolute angle of the resolver of the first phase and the absolute angle of the resolver of the second phase to the MCU with an incremental signal A/B pulse. According to claim 1,
The R/D converter,
A resolver offset correction device of an inverter that provides the absolute angle of the resolver of the first phase and the absolute angle of the resolver of the second phase to the MCU through serial or parallel communication. According to claim 1,
The first phase,
U phase, -U phase, V phase, -V phase, W phase or -W phase,
Resolver offset correction device of the inverter, characterized in that the U phase or -U phase for the simplification of the formula. According to claim 4,
The second phase,
It is a phase different from the first phase,
Preferably, the resolver offset correction device of the inverter, characterized in that the V phase or -V phase. a) forcibly aligning the motor rotor with respect to the first phase under the control of the MCU;
b) detecting an absolute angle of the rotor using a resolver in a state in which the rotor of the motor is forcibly aligned with respect to the first phase;
c) forcibly aligning the motor rotor with respect to a second phase different from the first phase;
d) detecting an absolute angle of the rotor in a resolver in a state in which the rotor is forcibly aligned with respect to the second phase; and
e) Equation 1 below using the absolute angles of the resolver detected in steps b) and d) and the electrical angle of the first phase and the electrical angle of the second phase respectively detected in steps a) and c) Resolver offset correction method of an inverter comprising the step of calculating through.
[Equation 1]
n = (2nd phase rotor electrical angle - 1st phase rotor electrical angle) / (2nd phase resolver absolute angle - 1st phase resolver absolute angle)
n is the ratio of the number of poles of the motor to the number of poles of the resolver According to claim 6,
The absolute angle of the resolver of the first phase and the absolute angle of the resolver of the second phase are
The resolver offset correction method of the inverter, characterized in that the output of the R / D converter that converts the analog output of the resolver into a digital signal. According to claim 7,
The absolute angle of the resolver of the first phase and the absolute angle of the resolver of the second phase are
A method for correcting a resolver offset of an inverter provided to the MCU as an A/B pulse, which is an incremental signal of the R/D converter. According to claim 7,
The absolute angle of the resolver of the first phase and the absolute angle of the resolver of the second phase are
A method for correcting a resolver offset of an inverter provided to the MCU through serial or parallel communication in the R / D converter.

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