Patent ID: 12218619

DETAILED DESCRIPTION

Hereinafter, reference will be made in detail to various embodiments of the present disclosure, examples of which are illustrated in the accompanying drawings and described below. While the disclosure will be described in conjunction with exemplary embodiments, it will be understood that the present description is not intended to limit the disclosure to the exemplary embodiments. On the contrary, the disclosure is intended to cover not only the exemplary embodiments, but also various alternatives, modifications, equivalents and other embodiments, which may be included within the spirit and scope of the disclosure as defined by the appended claims.

FIG.5is a configuration diagram illustrating a system for detecting a resolver signal of a motor according to the present disclosure.

As illustrated inFIG.5, a sine wave or a cosine wave, which is a resolver output signal, is output from a resolver100to a controller200.

The resolver100is a type of position sensor for detecting an absolute position angle of a motor rotor, which converts an excitation signal in the form of a square wave according to motor driving into a sine wave or a cosine wave using a filter included in a resolver circuit, and then outputs the sine wave or the cosine wave to the controller200.

Accordingly, a resolver output signal, which is a sine wave or a cosine wave, may be output from the resolver100to the controller200.

The controller200is configured to be able to primarily remove noise of the resolver output signal output from the resolver100using a first bandpass filter, then completely remove noise in the resolver output signal through a continuous moving average calculation process for the resolver output signal and a lead compensation process for phase compensation, and accurately detect a peak magnitude, a peak time, a peak point, etc. of the resolver output signal.

To this end, as illustrated inFIG.5, the controller200includes a first bandpass filter201, a moving average processor202, and a lead phase compensator203.

The first bandpass filter201serves to primarily remove noise introduced into the resolver output signal.

However, even when the resolver output signal output from the resolver100passes through the first bandpass filter201, some noise is not completely removed, and a magnitude change and a phase delay time of the resolver output signal may occur. In order to solve this problem, the controller200of the present disclosure includes the moving average processor202, and the lead phase compensator203.

The moving average processor202is configured to perform the continuous moving average calculation process for the resolver output signal passing through the first bandpass filter201to remove residual noise included in the resolver output signal without changing the magnitude of the resolver output signal.

To this end, when continuous data (resolver output signal of a predetermined period passing through the first bandpass filter) is sequentially input to n preset buffers, the moving average processor202is configured to repeatedly calculate an average for each piece of the sequentially input data.

The n is the predetermined number of buffers.

For example, as illustrated inFIG.7, when the moving average processor202repeats a process of calculating an average for data (resolver output signal of a predetermined period passing through the first bandpass filter) sequentially input to n preset buffers202-1, a process of excluding data input to a last buffer among the n buffers202-1, a process of moving data input to the n buffers202-1to adjacent buffers202-1, a process of inputting new data to a first buffer among the n buffers202-1, and a process of further calculating an average for data input to the n buffers202-1including the newly input data, noise included in the resolver output signal may be completely removed, and a magnitude of the resolver output signal from which noise is removed may be maintained at an original signal magnitude (original magnitude of the resolver output signal before introduction of noise output from the resolver).

As described above, the resolver output signal after passing through the first bandpass filter201and the moving average processor202in order may be in a state in which noise is completely removed without magnitude change.

Preferably, the number of pieces of data for the moving average for the output signal of the resolver passing through the first bandpass filter may be determined by dividing a sampling frequency of a predetermined specific period by a frequency of the output signal of the resolver.

At this time, the resolver output signal passing through the first bandpass filter201and the moving average processor202may be maintained at the original signal magnitude with residual noise removed. However, a phase difference and a phase delay may occur compared to the original signal.

To this end, the lead phase compensator203is configured to compensate a phase of the resolver output signal after passing through the moving average processor202to a phase level of an original signal (resolver output signal before passing through the moving average processor).

More specifically, the lead phase compensator203is a type of filter for phase compensation, and is configured to detect a phase difference between the resolver output signal before passing through the moving average processor202and the resolver output signal after passing through the moving average processor202, and then compensate the phase of the resolver output signal after passing through the moving average processor202to a phase level thereof before passing through the moving average processor202based on the detected phase difference.

To this end, the lead phase compensator203is configured to determine the phase to be compensated according to Equation 1 below.

GleadComp(s)=k⁢1+s/ωo1+s/ωp.[Equation⁢1]

In Equation 1 above, GleadComp(s) may be defined as a phase to be compensated, k denotes a gain value, ωomay be defined as the same value as a frequency value of the original signal (the resolver output signal before passing through the moving average processor), and ωpmay be defined as a value set larger than the frequency value of the original signal (the resolver output signal before passing through the moving average processor).

More specifically, ωomay be defined as 2×π×fo(the frequency of the original signal), and the ωpmay be defined as 2×π×fp(a value set larger than the frequency of the original signal for phase compensation).

At this time, when the value ωpis greater than the value ωo(ωp>ωo), the phase of the output signal is advanced with respect to the input signal. Therefore, the value ωpneeds to be set to a value greater than the value ωo.

Accordingly, using the value ωoand the value ωp, the phase of the resolver output signal after passing through the moving average processor may be compensated (for example, +2.5°) to the phase level before passing through the moving average processor.

Meanwhile, as illustrated inFIG.5, the controller200further includes a differentiator204, a second bandpass filter205, a reference point detector206, a peak time detector207, an edge time detector208, a subtractor209, a limiter210for limiting the peak time to prevent malfunction, a delay time calculator211, etc.

The differentiator204differentiates a resolver output signal passing through the moving average processor202to remove noise and passing through the lead phase compensator203to have a compensated phase, and outputs the differentiated resolver output signal.

The second bandpass filter205filters the differentiated resolver output signal output from the differentiator204to extract a signal in a preset specific band.

The reference point detector206detects a point in time (for example, point of 0 V) at which the differentiated resolver output signal passing through the second bandpass filter205satisfies a reference voltage.

The peak time detector207detects the peak time of the resolver output signal based on the point in time detected by the reference point detector206.

The edge time detector208detects an edge time of a square wave signal. At this time, the edge point detector208detects a frequency and amplitude of the square wave signal.

The subtractor209subtracts the edge time of the square wave signal detected by the edge time detector208from the peak time of the resolver output signal detected by the peak time detector207.

When a result subtracted by the subtractor209(peak time of the resolver output signal subtracted by the edge time of the square wave signal) is outside of a reference range, the limiter210removes the subtracted result to prevent malfunction.

The delay time calculator211calculates a phase delay time based on the peak time of the resolver output signal subtracted by the subtractor209(the peak time of the resolver output signal subtracted by the edge time of the square wave signal).

Here, a method of detecting a resolver signal of a motor based on the above configuration will be described in order as follows.

FIG.6is a flowchart illustrating a method for detecting the resolver signal of the motor according to the present disclosure.

First, a sine wave or a cosine wave, which is a resolver output signal, is output from the resolver100to the controller200when the motor is driven.

The resolver100converts an excitation signal in the form of a square wave according to motor driving into a sine wave or a cosine wave using a filter included in a resolver circuit, and then outputs the sine wave or the cosine wave to the controller200.

At this time, when harmonic noise, etc. is introduced into the sine wave or cosine wave, which is the resolver output signal, the resolver output signal into which the noise is introduced is input to the controller200(S101).

Then, the resolver output signal into which the noise is introduced passes through the first bandpass filter201of the controller200(S102).

Accordingly, the noise introduced into the resolver output signal may be primarily removed by the first bandpass filter201of the controller200.

However, even when the resolver output signal output from the resolver100passes through the first bandpass filter201, some noise is not completely removed, and a magnitude change and a phase delay time of the resolver output signal may occur.

In order to solve this problem, the resolver output signal passing through the first bandpass filter201passes through the moving average processor202(S103), and then passes through the lead phase compensator203(S104).

As described above with reference toFIG.7, the moving average processor202repeats a process of calculating an average for data (resolver output signal of a predetermined period passing through the first bandpass filter) sequentially input to n preset buffers202-1, a process of excluding data input to a last buffer among the n buffers202-1, a process of moving data input to the n buffers202-1to adjacent buffers202-1, a process of inputting new data to a first buffer among the n buffers202-1, and a process of further calculating an average for data input to the n buffers202-1including the newly input data.

Through the continuous moving average calculation process for the resolver output signal of the moving average processor202as described above, the noise included in the resolver output signal may be completely removed, and the magnitude of the resolver output signal from which the noise is removed may be maintained at the original signal magnitude (the original magnitude of the resolver output signal before introduction of noise output from the resolver).

At this time, the resolver output signal passing through the first bandpass filter201and the moving average processor202may be maintained at the original signal magnitude with residual noise removed. However, a phase difference and a phase delay may occur compared to the original signal.

To this end, when the resolver output signal passes through the lead phase compensator203after passing through the moving average processor202, the phase of the resolver output signal may be compensated to a phase level of the original signal (the resolver output signal before passing through the moving average processor).

To this end, the lead phase compensator203determines the phase to be compensated based on Equation 1 above. As described above, using the value ωodefined as 2×π×fo(frequency of the original signal) and the value ωp(value set to be larger than the frequency of the original signal for phase compensation), the phase of the resolver output signal after passing through the moving average processor may be compensated (for example, +2.5°) to the phase level before passing through the moving average processor.

As described above, it is possible to primarily remove noise of the resolver output signal output from the resolver100using the first bandpass filter, then completely remove noise in the resolver output signal through the continuous moving average calculation process for the resolver output signal and the lead compensation process for phase compensation, and accurately detect a peak magnitude, a peak time, a peak point, etc. of the resolver output signal.

Next, a process of calculating a substantial phase delay time, etc. of the resolver output signal is further performed using the differentiator204, the second bandpass filter205, the reference point detector206, the peak time detector207, the edge time detector208, the subtractor209, the limiter210, the delay time calculator211, etc. included in the controller200.

To this end, first, the resolver output signal passing through the lead phase compensator203is differentiated by the differentiator204(S105), and the differentiated resolver output signal is filtered by the second bandpass filter205(S106).

In more detail, the resolver output signal passing through the first bandpass filter201passes through the moving average processor202to remove noise and passes through the lead phase compensator203to output the resolver output signal having the compensated phase, the resolver output signal having the compensated phase passes through the differentiator204and is differentiated by the differentiator204to output the differentiated resolver output signal, and the differentiated resolver output signal output from the differentiator204passes through the second bandpass filter205and is filtered by the second bandpass filter205to extract a signal in a preset specific band.

Next, the reference point detector206detects a point in time (for example, point of 0 V) at which the differentiated resolver output signal passing through the second bandpass filter205satisfies the reference voltage (S107), and the peak time detector207detects the peak time of the resolver output signal based on the time detected by the reference point detector206(S108).

Subsequently, calculation of subtracting the edge time of the square wave signal from the peak time of the detected resolver output signal is performed (S109).

In more detail, a process of detecting the edge time of the square wave signal by the edge time detector208, and a process of subtracting the edge time of the square wave signal detected by the edge time detector208from the peak time of the resolver output signal detected by the peak time detector207by the subtractor209are performed.

Next, the delay time calculator211calculates a phase delay time based on the peak time of the resolver output signal subtracted by the subtractor209(tpk, the peak time of the resolver output signal subtracted by the edge time of the square wave signal).

Preferably, when the peak time of the resolver output signal subtracted by the subtractor209(tpk, the peak time of the resolver output signal subtracted by the edge time of the square wave signal) falls within a reference range (tpk−Δt<tpk<tpk+Δt, Δt is 2 μs as an example), the delay time calculator211calculates the phase delay time based thereon.

As such, when the substantial phase delay time of the resolver output signal is calculated using the differentiator204, the second bandpass filter205, the reference point detector206, the peak time detector207, the edge time detector208, the subtractor209, the limiter210, the delay time calculator211, etc. included in the controller200, the first bandpass filter201and the moving average processor202are used to completely remove noise introduced into the resolver output signal and maintain the magnitude of the resolver output signal at the original magnitude without change, and the phase compensation process of the lead phase compensator203is used to compensate the phase delay time for the resolver output signal. As a result, the substantial phase delay time of the resolver output signal may be accurately calculated.

TEST EXAMPLES

Test Example 1

FIG.10Ais a graph of measuring a peak time and a peak magnitude of the resolver output signal at a motor speed of 0 RPM by applying a resolver signal detection method for the motor according to the present disclosure and an existing resolver signal detection method, andFIG.10Bis a graph of measuring a peak time and a peak magnitude of the resolver output signal at a motor speed of 14,000 RPM by applying the resolver signal detection method for the motor according to the present disclosure and the existing resolver signal detection method.

As an embodiment of the present disclosure, inverter switching was performed at motor speeds of 0 RPM and 14,000 RPM, respectively, to output a resolver output signal from the resolver, the output resolver output signal was sequentially passed through the first bandpass filter201, the moving average processor202, and the lead phase compensator203, and then a peak time and a peak magnitude of the resolver output signal were measured.

As a comparative example, inverter switching was performed at motor speeds of 0 RPM and 14,000 RPM, respectively, to output a resolver output signal from the resolver, the output resolver output signal was only passed through the first bandpass filter201as in the past, and then a peak time and a peak magnitude of the resolver output signal were measured.

As a result of measurement, it was found that the peak time and the peak magnitude of the resolver output signal according to the embodiment of the present disclosure were constantly and accurately measured without significant fluctuation within the reference range as indicated inFIGS.10A and10B. On the other hand, it was found that the peak time and the peak magnitude of the resolver output signal according to the comparative example (existing) were irregularly and inaccurately measured such that the resolver output signal was outside of the reference range as indicated inFIGS.10A and10B.

As can be seen from the above Test Example 1, when the resolver output signal is sequentially passed through the first bandpass filter201, the moving average processor202, and the lead phase compensator203, the peak time and magnitude of the resolver output signal used for motor control may be accurately measured. Accordingly, it is possible to improve the precision of motor control.

Test Example 2

FIG.11Ais a graph of measuring a peak time for each motor RPM by applying the existing resolver signal detection method, andFIG.11Bis a graph of measuring a peak time for each motor RPM by applying the resolver signal detection method according to the present disclosure.

As a comparative example, inverter switching was performed for each motor speed (0 RPM, 5,000 RPM, 10,000 RPM, and 14,000 RPM) to output a resolver output signal from the resolver, the output resolver output signal was passed only through the first bandpass filter201as in the past, and then a peak time of the resolver output signal was measured.

As an embodiment of the present disclosure, inverter switching was performed for each motor speed (0 RPM, 5,000 RPM, 10,000 RPM, and 14,000 RPM) to output a resolver output signal from the resolver, the output resolver output signal was sequentially passed through the first bandpass filter201, the moving average processor202, and the lead phase compensator203, and then a peak time of the resolver output signal was measured.

As a result of measurement, in the case of the comparative example (existing), as illustrated inFIG.11A, it was found that an error of ±20 to 30 μs occurred in the peak time of the resolver output signal for each motor speed (0 RPM, 5,000 RPM, 10,000 RPM, and 14,000 RPM) compared to an average reference value (for example, 31 μs).

On the other hand, in the case of the present disclosure, as illustrated inFIG.11B, it was found that only a minute error of ±1 μs was present in the peak time of the resolver output signal for each motor speed (0 RPM, 5,000 RPM, 10,000 RPM, and 14,000 RPM) compared to the average reference value (for example, 31 μs).

As can be seen from Test Example 2 above, when the resolver output signal is sequentially passed through the first bandpass filter201, the moving average processor202, and the lead phase compensator203, the peak time of the resolver output signal used to control the motor for each RPM of the motor may be accurately measured, and accordingly, precision of the motor control may be improved.

Test Example 3

FIGS.12A and12Bare graphs comparing output power of the motor before and after a phase delay is reduced by the resolver signal detection method for the motor according to the present disclosure.

As a comparative example (existing), after passing the resolver output signal output from the resolver through only the first bandpass filter201as in steps S101to S102described above, steps S105to S109were performed to measure a substantial phase delay time (for example, 2 μs) of the resolver output signal, and driving power of the controlled motor (for example, controlling the motor speed at 1,000 RPM in a slope driving situation of an electric vehicle) was measured based on the measured phase delay time (for example, 2 μs). A result thereof is illustrated inFIG.12A.

As an embodiment of the present disclosure, after sequentially passing the resolver output signal output from the resolver through the first bandpass filter201, the moving average processor202, and the lead phase compensator203as in steps S101to S104described above, steps S105to S109were performed to measure a substantial phase delay time of the resolver output signal, and driving power of the controlled motor (for example, controlling the motor speed at 1,000 RPM in a slope driving situation of an electric vehicle) was measured based on the measured phase delay time (for example, 0.1 μs). A result thereof is illustrated inFIG.12B.

As a result of measurement, in the case of the comparative example (existing), as illustrated inFIG.12A, it was found that a large error occurred between driving power having a phase delay time (for example, 2 μs) and motor driving power of a normal level. On the other hand, in the case of the present disclosure, as illustrated inFIG.12B, it was found that an error between driving power having a phase delay time (for example, 0.1 μs) and motor driving power of a normal level was greatly reduced.

As can be seen from the above Test Example 2, the resolver signal detection system for the motor according to the present disclosure may be applied to a driving power control system for the motor to improve control precision thereof.

According to some aspects, the controller200and the components such as a first bandpass filter201, the moving average processor202, the lead phase compensator203, the differentiator204, the second bandpass filter205, the reference point detector206, the peak time detector207, the edge time detector208, the subtractor209, the limiter210, and the delay time calculator211may be implemented by circuits and/or an instruction in a form of software stored in a storage of the controller. When a processor of the controller200reads and executes the software, the processor of the controller200may be configured to cause the various components of the controller200to perform the corresponding operations.

Through the means for solving the above problems, the present disclosure provides the following effects.

First, by passing noise of the resolver output signal output from the resolver through the first bandpass filter and the moving average processor, it is possible to completely remove noise introduced into the resolver output signal, and to maintain the magnitude of the resolver output signal at the original magnitude without change.

Second, the phase delay time for the resolver output signal is allowed to be compensated by using the phase compensation process of the lead phase compensator for the resolver output signal passing through the first bandpass filter and the moving average processor, so that the peak magnitude, the peak time, and the peak point of the resolver output signal may be accurately detected.

Third, as noise removal, magnitude maintenance, and phase delay time compensation for the resolver output signal are performed, precision of motor control using the resolver output signal may be greatly improved.

The disclosure has been described in detail with reference to preferred embodiments thereof. However, it will be appreciated by those skilled in the art that changes may be made in these embodiments without departing from the principles and spirit of the disclosure, the scope of which is defined in the appended claims and their equivalents.