Vehicle permanent magnet synchronous motor speed detection device and method

Abstract

The application provides a detection device and method based on the rotation speed of a vehicle permanent magnet synchronous motor. The detection device comprises a phase discriminator, a loop filter and a voltage-controlled oscillator. The phase discriminator is used to obtain a measured position signal of the rotor of the vehicle permanent magnet synchronous motor at the current time, and obtain a phase difference according to the signal and an estimated position signal at the current time obtained from the voltage-controlled oscillator. The loop filter is used to filter and process the phase difference according to a first gain value and a second gain value, so as to obtain an estimated rotation speed and an estimated position differential at the current time. The voltage-controlled oscillator is used to integrate the estimated position differential, so as to obtain the estimated position signal at the current time. The application utilizes the phase-locked loop principle to design the detection device which can adaptively correct the phase of the estimated position signal and adaptively adjust the bandwidth of the loop filter according to the actual working condition, so that the detected rotation speed is more accurate, and the control precision of the control system is improved.

Description

Technical Field

[0001] This application relates to the field of electric vehicle motors, and more particularly to a device and method for detecting the speed of a vehicle permanent magnet synchronous motor. Background Technology

[0002] In the field of electric vehicles, permanent magnet synchronous motors (PMSMs) serve as the power source, converting electrical energy into kinetic energy through excitation provided by permanent magnets. The control accuracy, stability, and related dynamic performance of an electric vehicle's control system are all related to the quality of the PMSM's rotational speed; even the safe operation of the entire vehicle is related to the rotational speed. Therefore, obtaining highly accurate rotational speeds has become a hot topic of concern for engineers in this field.

[0003] In existing technologies, the rotational speed is usually calculated based on the rotor position signal of the permanent magnet synchronous motor. This method can be specifically: period measurement method, frequency measurement method, or frequency / period measurement method.

[0004] However, the methods used in the existing technology have certain limitations on the rotational speed. For example, the period measurement method can only be applied to lower rotational speeds, and the frequency measurement method can only be applied to higher rotational speeds. At the same time, when acquiring the position signal of the permanent magnet synchronous motor rotor in the existing technology, there are interferences from factors such as harmonics and sampling noise. Even if the acquired position signal is filtered, the low-frequency part of some interference factors will still be retained, which makes the phase delay of the rotational speed signal too large, resulting in inaccurate acquisition of the rotational speed. Summary of the Invention

[0005] This application provides a device and method for detecting the speed of a vehicle permanent magnet synchronous motor, which solves the problem that the speed and position signals collected in the prior art are not accurate enough.

[0006] In a first aspect, this application provides a detection device for the speed of a vehicle-mounted permanent magnet synchronous motor, the detection device comprising: a phase detector, a loop filter, and a voltage-controlled oscillator; wherein,

[0007] The phase detector is used to acquire the measured position signal of the rotor in the vehicle permanent magnet synchronous motor at the current moment, and to acquire the phase difference based on the measured position signal and the estimated position signal at the current moment acquired from the voltage-controlled oscillator.

[0008] The loop filter is used to filter the phase difference based on the first gain value and the second gain value to obtain the estimated speed and estimated position differential of the vehicle permanent magnet synchronous motor at the current moment.

[0009] The voltage-controlled oscillator is used to perform integration processing based on the estimated position derivative to obtain the estimated position signal at the current moment.

[0010] In one specific embodiment, the loop filter includes: a gain processing module and an integration module; wherein,

[0011] The gain processing module is used to apply the following formula based on the phase difference ε(t) and the first gain value K1:

[0012]

[0013] Obtain the derivative of the estimated rotational speed

[0014] The integration module is used to differentiate the estimated rotational speed. Perform integration to obtain the estimated rotational speed of the vehicle-mounted permanent magnet synchronous motor at the current time t.

[0015] The gain processing module is also used to calculate the estimated speed of the automotive permanent magnet synchronous motor. The second gain value K2 and the phase difference ε(t) are expressed by the following formula:

[0016]

[0017] Obtain the estimated position differential

[0018] Wherein, the current time t is a positive integer.

[0019] In one specific implementation, the voltage-controlled oscillator is used for:

[0020] Based on the estimated position signal of the previous time t-1 of the current time. The estimated position differential Formula used:

[0021]

[0022] Obtain the estimated position signal at the current time.

[0023] In one specific embodiment, the voltage-controlled oscillator is further used to apply the following formula:

[0024]

[0025] The estimated position signal at the current time Perform correction processing to obtain the corrected estimated position signal.

[0026] The phase detector is also used for:

[0027] Based on the measured position signal θ(t) and the corrected estimated position signal Formula used:

[0028]

[0029] Obtain the phase difference ε(t).

[0030] In one specific embodiment, the loop filter further includes: a gain adjustment module;

[0031] The gain adjustment module is used to acquire the frequency of the measurement position signal at the current moment or the rate of change of the frequency of the measurement position signal at the current moment.

[0032] The gain adjustment module is further configured to adjust the first gain value and the second gain value when the frequency of the measured position signal at the current time or the rate of change of the measured position signal frequency at the current time meets the gain adjustment condition.

[0033] In one specific embodiment, the gain adjustment module is specifically used for:

[0034] Based on the differential of the measured position signal at the current time t The differential of the measurement position signal at the previous time t-1 at the current time Formula used:

[0035]

[0036] Obtain the rate of change of frequency Δf(t) of the measured position signal based on the current time.

[0037] Wherein, Δt represents the sampling period for acquiring and measuring the position signal.

[0038] In one specific implementation, the first gain value and the second gain value satisfy:

[0039]

[0040] When the frequency of the measured position signal at the current moment increases, the gain adjustment module reduces the bandwidth ω0 of the loop filter to adjust the first gain value and the second gain value.

[0041] Alternatively, when the frequency of the measured position signal at the current moment decreases, the gain adjustment module increases the bandwidth ω0 of the loop filter to adjust the first gain value and the second gain value.

[0042] Secondly, this application provides a method for detecting the speed of a vehicle-mounted permanent magnet synchronous motor. This method is applied to the aforementioned detection device for detecting the speed of a vehicle-mounted permanent magnet synchronous motor, and the detection method includes:

[0043] The phase detector acquires the measured position signal of the rotor in the vehicle permanent magnet synchronous motor at the current moment, and obtains the phase difference based on the measured position signal and the estimated position signal at the current moment acquired from the voltage-controlled oscillator;

[0044] The loop filter performs filtering on the phase difference based on the first gain value and the second gain value to obtain the estimated speed and estimated position differential of the vehicle permanent magnet synchronous motor at the current moment.

[0045] The voltage-controlled oscillator performs integration based on the estimated position derivative to obtain the estimated position signal at the current moment.

[0046] In one specific embodiment, the loop filter includes: a gain processing module and an integration module;

[0047] The detection method includes:

[0048] The gain processing module uses the following formula based on the phase difference ε(t) and the first gain value K1:

[0049]

[0050] Obtain the derivative of the estimated rotational speed

[0051] The integrator module differentiates the estimated rotational speed. Perform integration to obtain the estimated rotational speed of the vehicle-mounted permanent magnet synchronous motor at the current time t.

[0052] The gain processing module is based on the estimated speed of the automotive permanent magnet synchronous motor. The second gain value K2 and the phase difference ε(t) are expressed by the following formula:

[0053]

[0054] Obtain the estimated position differential

[0055] Wherein, the current time t is a positive integer.

[0056] In one specific implementation, the voltage-controlled oscillator is based on the estimated position signal from the previous time t-1 at the current time. The estimated position differential Formula used:

[0057]

[0058] Obtain the estimated position signal at the current time.

[0059] In one specific implementation, the voltage-controlled oscillator adopts the following formula:

[0060]

[0061] The estimated position signal at the current time Perform correction processing to obtain the corrected estimated position signal.

[0062] The phase detector then uses the measured position signal θ(t) and the corrected estimated position signal... Formula used:

[0063]

[0064] Obtain the phase difference ε(t).

[0065] In one specific embodiment, the loop filter further includes: a gain adjustment module;

[0066] The detection method includes:

[0067] The gain adjustment module acquires the frequency of the measurement position signal at the current moment or the rate of change of the frequency of the measurement position signal at the current moment;

[0068] When the frequency of the measured position signal at the current time or the rate of change of the measured position signal frequency at the current time meets the gain adjustment condition, the gain adjustment module adjusts the first gain value and the second gain value.

[0069] In one specific embodiment, the detection method further includes:

[0070] The gain adjustment module adjusts the gain based on the differential of the measured position signal at the current time t. The differential of the measurement position signal at the previous time t-1 at the current time Formula used:

[0071]

[0072] Obtain the rate of change of frequency Δf(t) of the measured position signal based on the current time.

[0073] Wherein, Δt represents the sampling period for acquiring and measuring the position signal.

[0074] In one specific implementation, the first gain value and the second gain value satisfy:

[0075]

[0076] The detection method includes:

[0077] When the frequency of the measured position signal at the current moment increases, the gain adjustment module reduces the bandwidth ω0 of the loop filter to adjust the first gain value and the second gain value.

[0078] Alternatively, when the frequency of the measured position signal at the current moment decreases, the gain adjustment module increases the bandwidth ω0 of the loop filter to adjust the first gain value and the second gain value.

[0079] This application provides a detection device and method for the rotational speed of a vehicle-mounted permanent magnet synchronous motor (PMSM). The detection device includes a phase detector, a loop filter, and a voltage-controlled oscillator (VCO). The phase detector is used to acquire the measured position signal of the rotor in the PMSM at the current moment, and to obtain the phase difference based on the measured position signal and the estimated position signal at the current moment acquired from the VCO. The loop filter is used to filter the phase difference based on a first gain value and a second gain value to obtain the estimated rotational speed and estimated position derivative of the PMSM at the current moment. The VCO is used to integrate the estimated position derivative to obtain the estimated position signal at the current moment. Compared with existing technologies, this embodiment utilizes the phase-locked loop (PLL) principle to design a detection device with a phase detector, loop filter, and voltage-controlled oscillator (VCO). The loop filter adaptively adjusts the first and second gain values ​​to eliminate interference based on actual operating conditions, such as excessively strong or weak noise interference, thereby enhancing the stability of the detection device. Simultaneously, the VCO quickly adjusts the phase difference in the phase detector to a stable state, improving detection efficiency. This removes speed limitations from the measurement capabilities of this detection device, making it applicable to any situation, and also resulting in more accurate acquisition of the rotational speed of the automotive permanent magnet synchronous motor. Attached Figure Description

[0080] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0081] Figure 1A schematic diagram of the structure of a detection device for the speed of a vehicle permanent magnet synchronous motor provided in this application;

[0082] Figure 2 A schematic diagram of another detection device structure based on the speed of a vehicle permanent magnet synchronous motor provided in this application;

[0083] Figure 3 A schematic diagram of another detection device structure based on the speed of a vehicle permanent magnet synchronous motor provided in this application;

[0084] Figure 4 This is a schematic diagram of a method for detecting the speed of a vehicle-mounted permanent magnet synchronous motor, as provided in this application. Detailed Implementation

[0085] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments made by those skilled in the art under the guidance of these embodiments are within the scope of protection of this application.

[0086] The terms “first,” “second,” “third,” “fourth,” etc. (if present) in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a particular order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of this application described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms “comprising” and “having,” and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0087] With the development of the new energy and automotive sectors, electric vehicles are gradually gaining market share in the automotive market. Research on electric vehicles has become a hot topic in the automotive research field, especially the research on their drive components. Permanent magnet synchronous motors, as drive components of electric vehicles, convert electrical energy into kinetic energy to provide power. The amount of power provided is closely related to the control precision of the entire vehicle and even its operational safety.

[0088] The power provided by the permanent magnet synchronous motor can be determined from its rotational speed information. In existing technologies, the rotational speed of the permanent magnet synchronous motor can be obtained using period measurement, frequency measurement, or period / frequency measurement methods. These methods first obtain the rotor position signal of the permanent magnet synchronous motor, then perform differential processing on the obtained position signal to obtain the rotational speed information. The obtained rotational speed information is then used to determine whether the current rotational speed matches the requirements of the control command issued by the control system. If they do not match, corresponding adjustments are made to meet the requirements of the current control command.

[0089] However, existing methods for obtaining the speed of permanent magnet synchronous motors (PMSMs) have limitations. For example, the periodic measurement method, which is related to the number of pulses, results in fewer detected pulses when the PMSM rotates at higher speeds because the time interval between two adjacent pulses in the pulse generator is shorter. This limits the periodic measurement method to measuring lower speeds. Similarly, the frequency measurement method, which determines the speed based on counts over a specified time, generates very few pulses when the motor is rotating slowly within that time. Therefore, the frequency measurement method is only suitable for measuring higher speeds. Even if both periodic and frequency measurement methods are used simultaneously to address the speed limitation issue, these existing methods are still susceptible to noise and electromagnetic interference during measurement, resulting in inaccurate speed readings and consequently, inaccurate control systems.

[0090] Based on the technical problems mentioned above, the inventive concept of this application is to make the method for detecting the speed of a permanent magnet synchronous motor more widely applicable and have a higher anti-interference ability, and to make the detected speed of the automotive permanent magnet synchronous motor more accurate.

[0091] Example 1

[0092] Figure 1 This is a schematic diagram of a device for detecting the speed of a vehicle-mounted permanent magnet synchronous motor, as provided in this application. Figure 1 As shown, the detection device includes a phase detector 102, a loop filter 102, and a voltage-controlled oscillator 103.

[0093] It should be noted that the detection device based on the speed of a vehicle permanent magnet synchronous motor is designed based on the phase-locked loop principle. That is, the phase of the position signal detected by the rotary transformer or Hall sensor is locked with the output position signal, thereby making the speed obtained from the detected position signal more accurate.

[0094] Specifically, the aforementioned phase detector is used to acquire the measured position signal of the rotor in the automotive permanent magnet synchronous motor at the current moment, and to obtain the phase difference based on the measured position signal and the estimated position signal at the current moment obtained from the voltage-controlled oscillator.

[0095] It should be noted that the phase detector 101 has two input terminals, one of which is used to receive the position signal detected in real time, and the other of which is used to receive the estimated position signal fed back by the detection device.

[0096] Furthermore, the position-related signals mentioned in this embodiment can be specifically quantified as angles, or they can be in other forms. This embodiment does not impose any specific limitations on this.

[0097] In this embodiment, the acquisition interval of the rotary transformer is set to 1ms. When the rotary transformer detects the position signal of the rotor in the permanent magnet synchronous motor, it records it as the measured position signal at the current moment and transmits the measured position signal to the phase detector 101. After receiving the measured position signal, the phase detector 101 retrieves the estimated position signal at the current moment, that is, the estimated position signal fed back mentioned above.

[0098] When the electric vehicle is first started, i.e., when the current time value is 1ms, the estimated position signal at the current time is 0; after the electric vehicle has been running for a period of time, i.e. when the current time value is greater than 1ms, the estimated position signal at the current time is the estimated position signal obtained by the detection device at the previous time.

[0099] After receiving signals from the two input terminals, the phase detector 101 performs a subtraction operation between the received measured position signal at the current time and the estimated position signal at the current time to obtain the phase difference at the current time.

[0100] Then, the obtained phase difference is sent to the loop filter 102 for processing. Specifically, the loop filter 102 is used to filter the phase difference according to the first gain value and the second gain value to obtain the estimated speed and estimated position differential of the permanent magnet synchronous motor at the current moment.

[0101] In this embodiment, the loop filter 102 can be used to remove high-frequency components and noise in the phase so that the phase difference between the measured position signal and the estimated position signal at the current moment in the phase detector 101 can be quickly stabilized and locked, making the detected rotation speed more accurate.

[0102] Specifically, the first gain value and the second gain value in the loop filter 102 are used to improve the stability of the detection device.

[0103] This can be understood as the first and second gain values ​​having a function similar to improving a basic amplifier, that is, sending part or all of the output signal of the amplifier circuit back to the input of the phase detector in a certain way, and affecting the input signal of the amplifier circuit. Thus, the actual signal at the input of the phase detector 101 includes not only the measured position signal, but also the estimated position signal fed back from the output, which helps in obtaining the estimated position signal. At the same time, referring to the fed-back estimated position signal helps improve the accuracy of the measured rotational speed.

[0104] Furthermore, the first gain value and the second gain value are related to the bandwidth in the loop filter 102 and can vary according to changes in the bandwidth.

[0105] More specifically, the differential of the estimated rotational speed can be obtained by multiplying the first gain value by the phase difference at the current moment. Similarly, the differential of the current position can be obtained by summing the product of the second gain value and the phase difference with the estimated rotational speed at the current moment.

[0106] The estimated rotational speed at the current moment has a similar meaning to the estimated position at the current moment mentioned above. That is, when the current moment is 1ms, the estimated rotational speed at the current moment is 0; when the current moment is greater than 1ms, the estimated rotational speed at the current moment is the estimated rotational speed of the previous moment.

[0107] Furthermore, when the differential of the estimated rotational speed at the current moment is obtained, the loop filter 102 performs integration processing on it to obtain the estimated rotational speed at the current moment. When the detection device is in a locked state, the obtained estimated rotational speed value can be determined as the rotational speed of the vehicle permanent magnet synchronous motor.

[0108] In order to accurately measure the speed of the vehicle permanent magnet synchronous motor in the next step, the loop filter 102 sends the estimated position differential at the current moment to the voltage-controlled oscillator.

[0109] Specifically, the voltage-controlled oscillator 103 is used to perform integration processing based on the estimated position derivative to obtain the estimated position signal at the current moment.

[0110] In this embodiment, the voltage-controlled oscillator 103 includes a capacitor. The charging and discharging operation of this capacitor can realize the oscillation circuit and can adaptively adjust the oscillation frequency according to the actual scenario. This helps the detection device maintain a stable difference between the input measured position signal and the output estimated position signal, which is beneficial for realizing the detection of the input measured position signal by the estimated position signal. This achieves synchronization between the externally detected position signal and the internally processed estimated position signal, enabling the detection device to continuously and accurately detect the rotational speed of the vehicle permanent magnet synchronous motor.

[0111] More specifically, the voltage-controlled oscillator 103 receives the estimated position signal of the current moment sent by the loop filter 102, performs integration processing, and then sums the integrated estimated position of the current moment with the estimated position signal of the previous moment to obtain the estimated position of the current moment.

[0112] In this embodiment, a detection device for the rotational speed of a vehicle-mounted permanent magnet synchronous motor (PMSM) is provided. The device includes a phase detector, a loop filter, and a voltage-controlled oscillator (VCO). The phase detector acquires the measured position signal of the rotor in the PMSM at the current moment and obtains the phase difference based on the measured position signal and the estimated position signal at the current moment acquired from the VCO. The loop filter filters the phase difference based on a first gain value and a second gain value to obtain the estimated rotational speed and estimated position derivative of the PMSM at the current moment. The VCO performs integration processing based on the estimated position derivative to obtain the estimated position signal at the current moment. Compared with existing technologies, this embodiment utilizes the phase-locked loop (PLL) principle to design a detection device with a phase detector, loop filter, and voltage-controlled oscillator (VCO). The loop filter adaptively adjusts the first and second gain values ​​to eliminate interference based on actual operating conditions, such as excessively strong or weak noise interference, thereby enhancing the stability of the detection device. Simultaneously, the VCO quickly adjusts the phase difference in the phase detector to a stable state, improving detection efficiency. This eliminates speed limitations, allowing the device to be used in any situation, and also results in more accurate acquisition of the speed of the automotive permanent magnet synchronous motor.

[0113] Example 2

[0114] Based on the above embodiment one, this embodiment specifically illustrates the specific structure and function of the detection device when the loop filter includes a gain processing module and an integration module. Figure 2 Another device for detecting the speed of a vehicle-mounted permanent magnet synchronous motor provided in this application, such as... Figure 2 As shown, the gain processing module 1021 is connected to the phase detector 101, the first gain value 10211 in the gain processing module is connected to the integration processing module 1022, and the first gain value 10212 is connected to the voltage-controlled oscillator.

[0115] The gain processing module 1021 is used to obtain the differential of the estimated rotational speed based on the phase difference and the first gain value.

[0116] In this embodiment, assuming the current time is represented as t, and t is an integer, the gain processing module can perform a product operation on the phase difference at the current time and the first gain value according to the following formula to obtain the differential of the estimated rotation speed at the current time.

[0117]

[0118] In the formula, ε(t) represents the differential of the estimated rotational speed, ε(t) represents the phase difference obtained at the current moment, and K1 represents the first gain value at the current moment.

[0119] After the gain processing module 1021 obtains the derivative of the estimated speed, it sends the obtained derivative of the estimated speed to the integration module 1022 in order to obtain the speed of the vehicle permanent magnet synchronous motor.

[0120] Specifically, the integrator module 1022 is used to differentiate the estimated rotational speed at the current moment. Perform integration to obtain the estimated rotational speed of the permanent magnet synchronous motor at the current time t.

[0121] In this embodiment, when the output estimated position signal of the detection device and the input measured position signal are locked, that is, when the phase difference remains stable, the estimated speed obtained by the integration module 1022 is the speed of the permanent magnet synchronous motor. If the position is unlocked, corresponding adjustment processing is required to obtain an accurate speed.

[0122] Corresponding to the phase-locked loop principle, so that the input measured position signal and the output estimated position signal can remain stable, the gain processing module 1021 also needs to perform gain processing on the estimated rotation speed so as to generate a differential signal related to the estimated position signal and use it as feedback information related to the input terminal of the phase detector 101.

[0123] Specifically, the gain processing module 1021 is also used to calculate the estimated speed of the automotive permanent magnet synchronous motor. The second gain value K2 and the phase difference ε(t) are given by the following formula:

[0124]

[0125] In the formula, This represents the differential of the estimated position at the current moment. K represents the estimated rotational speed at the current moment, K2 represents the second gain value at the current moment, and ε(t) represents the phase difference at the current moment.

[0126] In this embodiment, after processing the phase difference in the phase detector 101 using the second gain value in the gain processing module of the loop filter 102, the estimated position differential is obtained, and then the estimated position differential is sent to the voltage-controlled oscillator 103 to obtain the estimated position signal.

[0127] In the embodiment, the specific uses of the gain processing module 1021 and the integration module 1022 in the loop filter are described in detail, and the specific manifestation of the role of the gain values ​​K1 and K2 in the loop filter as a stable detection device is explained, which lays the foundation for obtaining accurate vehicle permanent magnet synchronous motor speed.

[0128] Example 3

[0129] Based on the above embodiment one or embodiment two, this embodiment specifically illustrates the specific function of the voltage-controlled oscillator in the detection device for the speed of a vehicle permanent magnet synchronous motor.

[0130] In this embodiment, the voltage-controlled oscillator can process the estimated position signal and the estimated position derivative of the previous time step according to the following formula to obtain the estimated position signal at the current time step:

[0131]

[0132] In the formula, This represents the estimated position signal at the current moment. It represents the estimated position signal of the previous time step at the current time step.

[0133] Furthermore, when the detection device is not in a locked state, the voltage-controlled oscillator can also correct the position signal at the current moment according to the following formula, so that the detection device enters a locked state, thereby making the detected speed of the vehicle permanent magnet synchronous motor more accurate.

[0134]

[0135] In the formula, This represents the corrected estimated position signal. This represents the estimated position signal obtained at the current time, and θ(t) represents the measured position at the current time.

[0136] This can be understood as follows: the phase range that the phase detector can identify is between -π and π, while the rotor of the automotive permanent magnet synchronous motor can rotate in both the forward and reverse directions. Therefore, the voltage-controlled oscillator needs to perform phase correction on the feedback signal "estimated position at the current moment" received by the phase detector so that the phase detector can work normally. That is, the estimated position at the current moment is quantized onto the reference of one revolution of the automotive permanent magnet synchronous motor rotor.

[0137] In other words, for the same starting point, the forward direction can rotate up to 180°, and the reverse direction can rotate up to 180°. Therefore, considering the actual situation, the obtained estimated position signal needs to be corrected.

[0138] Specifically, the estimated position signal at the current moment. When the rotation direction represented by the sensor and the rotation direction of the measured position at the current moment are both positive, and the estimated position signal at the current moment... When the sum of the measured position signal and π at the current moment is greater than θ(t) + π, it indicates that the estimated position signal at the current moment has exceeded the range of the possible positive direction of rotation. Therefore, in order to correct the estimated position signal at the current moment to be between [-π, π], we can start from the opposite direction of rotor rotation, that is, the corrected estimated position signal is...

[0139] Similarly, the estimated position at the current moment When both the rotation direction represented by the current measured position and the current position are negative, according to the above processing principle, the estimated position signal at the current moment can be obtained. Revised to

[0140] For cases where the rotations are not in the same opposite direction, or where the above judgment conditions are not met, no phase correction is performed.

[0141] Correspondingly, after the estimated position signal is corrected by the voltage-controlled oscillator 103, it is fed back to the phase detector 101. The phase detector 101 then calculates the phase difference again based on the current position signal and the corrected estimated position signal.

[0142] Specifically, the phase detector 101 measures the position signal θ(t) and the corrected estimated position signal. The phase difference ε(t) is obtained using the following formula.

[0143]

[0144] This embodiment elaborates on the specific functions of the voltage-controlled oscillator (VCO) and the specific processing procedures for implementing these functions. The feedback signal obtained from the VCO helps the detection device to continuously measure and acquire the speed of the automotive permanent magnet synchronous motor.

[0145] Example 4

[0146] Based on the above embodiments two and three, this embodiment specifically illustrates the specific structure of the detection device when the loop filter also includes a gain adjustment module, and the specific function corresponding to the structure. Figure 3 Another type of speed detection device based on a vehicle permanent magnet synchronous motor provided in this application is as follows: Figure 3 As shown, the gain adjustment module 1023 is connected to the gain processing module 1021, and the second gain value combination in the gain adjustment module 1023 and the gain processing module 1021 is input to the voltage-controlled oscillator 103.

[0147] In this embodiment, the gain adjustment module 1023 is used to obtain the frequency of the measurement position signal at the current time or the rate of change of the frequency of the measurement position signal at the current time; at the same time, the gain adjustment module 1023 can also be used to adjust the first gain value and the second gain value when the frequency of the measurement position signal at the current time or the rate of change of the frequency of the measurement position signal at the current time meets the gain adjustment condition.

[0148] Specifically, the detection accuracy of this detection device is affected by factors such as the filtering effect, the speed at which the output estimated position signal is detected and measured as the position limit, and the phase difference under steady state. These factors are all related to the bandwidth of the loop filter. The bandwidth of the loop filter refers to the degree of noise suppression; the smaller the bandwidth, the stronger the noise suppression capability of the loop filter.

[0149] In this embodiment, considering the different operating conditions of the vehicle permanent magnet synchronous motor, the gain adjustment module 1023 is used to adaptively adjust the bandwidth value in the loop filter according to different operating conditions, so as to ensure that the detection device designed based on the phase-locked loop principle can obtain good detection effect in the entire operating range.

[0150] Considering that when the frequency of the measured position signal is low, the distortion of the amplitude of the measured position signal by the detection device decreases, that is, the noise suppression effect is enhanced; conversely, when the frequency of the measured position signal is high, the distortion of the amplitude of the measured position signal by the detection device increases, that is, the noise suppression effect is weakened, the relationship between the frequency of the measured position signal and the bandwidth value of the loop filter is: the higher the frequency of the measured position signal, the smaller the bandwidth value.

[0151] Therefore, the bandwidth value in the loop filter 102 can be determined based on the frequency of the measured position signal at the current moment to ensure that the detection device captures the speed of the estimated rotational speed at the current moment.

[0152] The estimated rotational speed obtained based on this detection device To measure the frequency of the position signal, assuming the bandwidth of the loop filter is ω0, the above correspondence can be transformed into: The larger the value, the smaller ω0 becomes.

[0153] Accordingly, in order to obtain the bandwidth value in the loop filter 102, the gain adjustment module 1023 needs to obtain the frequency of the measured position signal at the current time, that is, the estimated rotation speed at the current time. The estimated rotation speed is related to the current time t. When t equals 1ms, the estimated rotation speed is 0; when t is greater than 1ms, the estimated rotation speed is the estimated rotation speed value at time t-1.

[0154] In this embodiment, the detection device has a pre-stored table of correspondence between frequency range and bandwidth. Based on this table, it can determine whether the bandwidth corresponding to the frequency value of the measured position obtained in real time is within a reasonable range. If not, the bandwidth value is adaptively adjusted.

[0155] For example, assuming a detection period of 1ms, the speed range of the permanent magnet synchronous motor to be detected is 0-18000 rpm and the corresponding frequency is 0-300Hz. When the detection device determines that the estimated speed value at the current moment is trending upwards, in order to ensure stable acquisition of the speed value of the automotive permanent magnet synchronous motor, the bandwidth value in the loop filter needs to be no less than ω. 0min Similarly, when the detection device determines that the current measurement position signal is at the maximum value of 300Hz within this frequency range, and the current measurement position signal is at a step input, the bandwidth in the loop filter needs to be set to be greater than or equal to ω. 0mid Correspondingly, when the detection device determines that the current measured position signal is at the maximum value of 300Hz in this frequency range, and the measured position signal at the current moment is at a step input, in order to enable the detection device to detect the speed value of the vehicle permanent magnet synchronous motor as quickly as possible, that is, to ensure that the measured position signal and the estimated position signal can be quickly locked, the bandwidth in the loop filter is set to be less than or equal to ω. 0max The relationship between the three parameters is as follows: ω 0min <ω 0mid <ω 0max .

[0156] In summary, to ensure that the measured position signal and the estimated position signal in the detection device reach a stable state, the bandwidth ω0 of the loop filter should be within the range of [ω 0min ω 0max ].

[0157] In other words, when the bandwidth value corresponding to the frequency of the measured position signal at the current moment is not in [ω 0min ω 0max If the bandwidth is within the specified range, adaptive bandwidth adjustment is required.

[0158] More specifically, the gain adjustment module 1023 can also determine the bandwidth value based on the rate of change of the frequency of the measured position signal at the current moment. The rate of change of the position signal can be obtained by the derivative of the measured position signal at the current moment and the derivative of the measured position signal at the previous moment.

[0159] For example, the gain adjustment module 1023 obtains the rate of change of the frequency of the measured position signal at the current moment according to the following formula.

[0160]

[0161] In the formula, Δf(t) represents the rate of change of the frequency of the measured position signal at the current moment. This represents the derivative of the measured position signal at the current time t. It represents the derivative of the measurement position signal at the previous time t-1, where Δt represents the sampling period of the measurement position signal acquisition, which is 1ms.

[0162] In real-world scenarios, considering the stable phase difference inherent in the detection device itself, a certain tracking error will also occur. Therefore, in order to ensure the tracking speed, it is necessary to appropriately increase the bandwidth value in the loop filter 102. However, increasing the bandwidth value means weakening the noise suppression effect in order to ensure the tracking speed.

[0163] Based on this, when the frequency of the measured position signal at the current moment is greater than the frequency of the measured position signal at the previous moment, this situation may be caused by the inherent stable phase difference of the detection device. Therefore, it is necessary to increase the frequency of the loop filter to ensure the tracking speed. The specific manifestation of this relationship is: the larger Δf(t) is, the larger ω0 is.

[0164] Similar to the above-described method of determining the bandwidth value based on the current position signal, in this embodiment, the detection device has a pre-stored table showing the relationship between the frequency change rate of the measured position signal and the bandwidth value. By determining the interval in which the frequency change rate of the current measured position signal falls, the bandwidth value is then determined.

[0165] Assuming C1 and C2 represent two threshold values ​​for the rate of change of frequency, and C1 < C2, and given that the detection device is designed based on the phase-locked loop principle, it also has three operating states: unlocked state (the phase difference between the measured position signal and the estimated position signal is changing), capture detection state (the process of adjusting the phase difference between the measured position signal and the estimated position signal), and locked state (the phase difference between the measured position signal and the estimated position signal is stable). Accordingly, the range of the rate of change of frequency is different when the detection device is in different operating states. That is, the unlocked state should satisfy: |Δf(t)| ≥ C2; the capture detection state should satisfy: C1 ≤ |Δf(t)| < C2; and the locked state should satisfy: |Δf(t)| < C1.

[0166] This can be understood as follows: when the detection device is in different working states, it is necessary to determine whether the rate of change of the measured position signal at the current moment matches the current working state. If they do not match, bandwidth adjustment processing is required to make the rate of change of the current position signal match the current working state of the detection device.

[0167] In addition, the gain adjustment module 1023 can also comprehensively consider the frequency and rate of change of the measured position signal. When the detection device is in different working states, it can establish a functional relationship between the bandwidth value and the frequency and rate of change of the measured position signal, and adjust the bandwidth value in turn to ensure the detection speed of the detection device more comprehensively.

[0168] In this embodiment, the functional relationship between the bandwidth value and the measured position signal and the rate of change is not specifically limited. Optionally, the functional relationship under different working conditions can be further illustrated by the following functional relationship as an example:

[0169] 1): In the unlocked state:

[0170] ω0=ω 0max

[0171] 2): In the capture and detection state:

[0172]

[0173] 3): In locked state:

[0174]

[0175] Specifically, the detection device determines whether the phase difference is in a stable state based on the phase difference obtained by the phase detector. If it is not, the current loop filter is adjusted according to the bandwidth under the aforementioned unlocked state, that is, the bandwidth is adjusted to ω. 0max In the capture detection state, if the detection device needs to stabilize the phase difference, it should adjust the bandwidth of the current loop filter accordingly, based on the formula corresponding to the capture detection state. If the detection device determines that the phase difference is stable, it should adjust the bandwidth of the current loop filter accordingly, based on the formula corresponding to the lock state. This ensures that the detection device can quickly reach the lock state, improving detection efficiency and accuracy.

[0176] After the gain adjustment module 1023 obtains the bandwidth value in the loop filter 102, it determines whether the frequency or rate of change of the position signal at the current moment meets the gain adjustment condition. If so, the first gain value and the second gain value are adjusted.

[0177] Specifically, when it is determined that the frequency or rate of change of the current position signal is not within the frequency range or rate of change range corresponding to the current bandwidth value, the first gain value and the second gain value are adjusted.

[0178] More specifically, the first gain value and the second gain value can be adjusted using the following formula.

[0179]

[0180] In the formula, ζ represents the transient characteristics of the detection device. In this embodiment, let ζ = ζ.

[0181]

[0182] This ensures that the performance of the detection device is optimized, that is, that the optimal detection speed is guaranteed, so that the detected rotational speed value is more accurate.

[0183] Correspondingly, when the frequency of the measured position signal at the current moment increases, the gain adjustment module 1023 reduces the bandwidth ω0 of the loop filter to adjust the first gain value and the second gain value; or, when the frequency of the measured position signal at the current moment decreases, the gain adjustment module increases the bandwidth ω0 of the loop filter to adjust the first gain value and the second gain value.

[0184] In this embodiment, the specific processing procedure of the gain adjustment module 1023 in the loop filter is explained in detail. The adjusted parameters are input into the gain processing module to update the first gain value and the second gain value, so as to ensure the detection speed of the detection device and thus make the detection device obtain the speed of the large vehicle permanent magnet synchronous motor more accurately.

[0185] Example 5

[0186] This embodiment provides a method for detecting the rotational speed of a vehicle permanent magnet synchronous motor. This method can be used on the detection device mentioned in any of the embodiments one to four above. Figure 4 This application provides a method for detecting the speed of a vehicle-mounted permanent magnet synchronous motor, such as... Figure 4 As shown, the method includes:

[0187] Step 401: The phase detector acquires the measured position signal of the rotor in the vehicle permanent magnet synchronous motor at the current moment, and obtains the phase difference based on the measured position signal and the estimated position signal at the current moment acquired from the voltage-controlled oscillator.

[0188] Step 402: The loop filter performs phase difference filtering based on the first gain value and the second gain value to obtain the estimated speed and estimated position differential of the permanent magnet synchronous motor at the current moment.

[0189] Step 403: The voltage-controlled oscillator performs integration processing based on the estimated position derivative to obtain the estimated position signal at the current moment.

[0190] Steps 401 to 403 described above are applied to the detection device mentioned in Embodiment 1, and the operating principle of this method is the same as that in Embodiment 1, so they will not be repeated here.

[0191] In one specific embodiment, step 402 specifically includes:

[0192] Step 4021: The gain processing module in the loop filter uses the formula based on the phase difference ε(t) and the first gain value K1:

[0193]

[0194] Obtain the derivative of the estimated rotational speed

[0195] Step 4022: The integrator module in the loop filter differentiates the estimated rotational speed. Perform integration to obtain the estimated rotational speed of the permanent magnet synchronous motor at the current time t.

[0196] Step 4023: The gain processing module in the loop filter calculates the estimated speed of the automotive permanent magnet synchronous motor. The second gain value K2 and the phase difference ε(t) are given by the following formula:

[0197]

[0198] Obtain the estimated position differential Where t is a positive integer.

[0199] Steps 4021 to 4023 described above are specifically applied to the detection device mentioned in Embodiment 2, and the operating principle of this method is the same as that in Embodiment 2, so they will not be repeated here.

[0200] In one specific implementation, step 403 specifically includes: the voltage-controlled oscillator using the estimated position signal from the previous time t-1 at the current time. Estimated position differential Formula used:

[0201]

[0202] Obtain the estimated position signal at the current time.

[0203] This specific implementation method is applied to the detection device mentioned in Embodiment 3, and the operating principle of the method is the same as that of Embodiment 3, so it will not be repeated here.

[0204] In one specific implementation, the voltage-controlled oscillator can also correct the phase of the measurement position at the current moment, including: the voltage-controlled oscillator uses the following formula:

[0205]

[0206] Estimated position signal at the current time Perform correction processing to obtain the corrected estimated position signal. The phase detector then measures the position signal. and the corrected estimated position signal Formula used:

[0207]

[0208] Obtain the phase difference ε(t).

[0209] This specific implementation method is applied to the detection device mentioned in Embodiment 3, and the operating principle of the method is the same as that of Embodiment 3, so it will not be repeated here.

[0210] In one specific implementation, when the loop filter further includes a gain adjustment module, the method includes: the gain adjustment module acquiring the frequency of the measurement position signal at the current moment or the rate of change of the frequency of the measurement position signal at the current moment; and the gain adjustment module adjusting the first gain value and the second gain value when the frequency of the measurement position signal at the current moment or the rate of change of the frequency of the measurement position signal at the current moment meets the gain adjustment condition.

[0211] This specific implementation method is applied to the detection device mentioned in Embodiment 4, and the operating principle of the method is the same as that of Embodiment 4, so it will not be repeated here.

[0212] In one specific implementation, the gain adjustment module acquires the frequency of the measured position signal at the current moment or the rate of change of the measured position signal frequency based on the current moment, including: the gain adjustment module based on the derivative of the measured position signal at the current moment t. The derivative of the measured position signal at the previous time t-1. Formula used:

[0213]

[0214] Obtain the rate of change Δf(t) of the frequency of the measurement position signal based on the current time; where Δt represents the sampling period of the acquired measurement position signal.

[0215] This specific implementation method is applied to the detection device mentioned in Embodiment 4, and the operating principle of the method is the same as that of Embodiment 4, so it will not be repeated here.

[0216] In one specific implementation, the first gain value and the second gain value satisfy:

[0217]

[0218] The method includes: when the frequency of the measured position signal at the current moment increases, the gain adjustment module reduces the bandwidth ω0 of the loop filter to adjust the first gain value and the second gain value; or, when the frequency of the measured position signal at the current moment decreases, the gain adjustment module increases the bandwidth ω0 of the loop filter to adjust the first gain value and the second gain value.

[0219] This specific implementation method is applied to the detection device mentioned in Embodiment 4, and the operating principle of the method is the same as that of Embodiment 4, so it will not be repeated here.

[0220] In this embodiment, a method for detecting the rotational speed of a vehicle-mounted permanent magnet synchronous motor (PMSM) is provided. A phase detector acquires the measured position signal of the rotor in the PMSM at the current moment, and obtains the phase difference based on the measured position signal and the estimated position signal at the current moment obtained from a voltage-controlled oscillator (VCO). A loop filter filters the phase difference based on a first gain value and a second gain value to obtain the estimated rotational speed and estimated position derivative of the PMSM at the current moment. The VCO performs integration processing based on the estimated position derivative to obtain the estimated position signal at the current moment. Compared with existing technologies, this embodiment utilizes the phase-locked loop (PLL) principle to design a detection method with a phase detector, a loop filter, and a VCO. The loop filter adaptively adjusts the first and second gain values ​​to eliminate interference factors according to actual operating conditions, such as excessively strong or low noise interference, thereby enhancing the stability of the detection device. Simultaneously, the VCO quickly adjusts the phase difference in the phase detector to a stable state, improving detection efficiency. This makes the measurement of rotational speed no longer limited by the magnitude of the speed, and can be used in any situation. At the same time, it makes the obtained rotational speed of automotive permanent magnet synchronous motors more accurate.

[0221] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A device for detecting the speed of a vehicle-mounted permanent magnet synchronous motor, characterized in that, include: Phase detector, loop filter, and voltage-controlled oscillator; among which, The phase detector is used to acquire the measured position signal of the rotor in the vehicle permanent magnet synchronous motor at the current moment, and to acquire the phase difference based on the measured position signal and the estimated position signal at the current moment acquired from the voltage-controlled oscillator. The loop filter is used to filter the phase difference based on the first gain value and the second gain value to obtain the estimated speed and estimated position differential of the vehicle permanent magnet synchronous motor at the current moment. The voltage-controlled oscillator is used to perform integration processing based on the estimated position derivative to obtain the estimated position signal at the current moment; The loop filter includes a gain adjustment module; The gain adjustment module is used to acquire the frequency of the measurement position signal at the current moment or the rate of change of the frequency of the measurement position signal at the current moment. The gain adjustment module is further configured to adjust the first gain value and the second gain value when the frequency of the measured position signal at the current time or the rate of change of the measured position signal frequency at the current time meets the gain adjustment condition. The gain adjustment module is specifically used to reduce the bandwidth of the loop filter when the frequency of the measured position signal at the current moment increases, so as to adjust the first gain value and the second gain value. Alternatively, when the frequency of the measured position signal at the current moment decreases, the gain adjustment module increases the bandwidth of the loop filter to adjust the first gain value and the second gain value.

2. The detection device for the speed of a vehicle permanent magnet synchronous motor according to claim 1, characterized in that, The loop filter further includes: a gain processing module and an integration module; wherein... The gain processing module is used to apply the following formula based on the phase difference ε(t) and the first gain value K1: Obtain the derivative of the estimated rotational speed The integration module is used to differentiate the estimated rotational speed. Perform integration to obtain the estimated rotational speed of the vehicle-mounted permanent magnet synchronous motor at the current time t. The gain processing module is also used to calculate the estimated speed of the automotive permanent magnet synchronous motor. The second gain value K2 and the phase difference ε(t) are expressed by the following formula: Obtain the estimated position differential Wherein, the current time t is a positive integer.

3. The detection device for the speed of a vehicle permanent magnet synchronous motor according to claim 1 or 2, characterized in that, The voltage-controlled oscillator is specifically used for: Based on the estimated position signal of the previous time t-1 of the current time. The estimated position differential Formula used: Obtain the estimated position signal at the current time.

4. The detection device for the speed of a vehicle permanent magnet synchronous motor according to claim 3, characterized in that, The voltage-controlled oscillator is also used to apply the following formula: The estimated position signal at the current time Perform correction processing to obtain the corrected estimated position signal. The phase detector is also used for: Based on the measured position signal θ(t) and the corrected estimated position signal Formula used: Obtain the phase difference ε(t).

5. The detection device for the speed of a vehicle permanent magnet synchronous motor according to claim 2, characterized in that, The gain adjustment module is specifically used for: Based on the differential of the measured position signal at the current time t The differential of the measurement position signal at the previous time t-1 at the current time Formula used: Obtain the rate of change of frequency Δf(t) of the measured position signal based on the current time. Wherein, Δt represents the sampling period for acquiring and measuring the position signal.

6. The detection device for the speed of a vehicle permanent magnet synchronous motor according to claim 5, characterized in that, The first gain value and the second gain value satisfy: Wherein, ω0 represents the bandwidth of the loop filter, K1 represents the first gain value, K2 represents the second gain value, and ζ represents the transient characteristics in the detection device.

7. A method for detecting the speed of a vehicle-mounted permanent magnet synchronous motor, characterized in that, The method applied to the detection device based on the speed of a vehicle permanent magnet synchronous motor as described in any one of claims 1 to 6 includes: The phase detector acquires the measured position signal of the rotor in the vehicle permanent magnet synchronous motor at the current moment, and obtains the phase difference based on the measured position signal and the estimated position signal at the current moment acquired from the voltage-controlled oscillator; The loop filter performs filtering on the phase difference based on the first gain value and the second gain value to obtain the estimated speed and estimated position differential of the vehicle permanent magnet synchronous motor at the current moment. The voltage-controlled oscillator performs integration processing based on the estimated position derivative to obtain the estimated position signal at the current moment; The loop filter further includes a gain adjustment module; therefore, the method includes: The gain adjustment module acquires the frequency of the measurement position signal at the current moment or the rate of change of the frequency of the measurement position signal at the current moment; When the frequency of the measured position signal at the current time or the rate of change of the measured position signal frequency at the current time meets the gain adjustment condition, the gain adjustment module adjusts the first gain value and the second gain value. The adjustment process for the first gain value and the second gain value includes: When the frequency of the measured position signal at the current moment increases, the gain adjustment module reduces the bandwidth of the loop filter to adjust the first gain value and the second gain value. Alternatively, when the frequency of the measured position signal at the current moment decreases, the gain adjustment module increases the bandwidth of the loop filter to adjust the first gain value and the second gain value.

8. The method for detecting the speed of a vehicle-mounted permanent magnet synchronous motor according to claim 7, characterized in that, The loop filter includes a gain processing module and an integration module; the loop filter performs filtering processing on the phase difference based on a first gain value and a second gain value to obtain the estimated speed and estimated position differential of the vehicle permanent magnet synchronous motor at the current moment, including: The gain processing module uses the following formula based on the phase difference ε(t) and the first gain value K1: Obtain the derivative of the estimated rotational speed The integrator module differentiates the estimated rotational speed. Perform integration to obtain the estimated rotational speed of the vehicle-mounted permanent magnet synchronous motor at the current time t. The gain processing module is based on the estimated speed of the automotive permanent magnet synchronous motor. The second gain value K2 and the phase difference ε(t) are expressed by the following formula: Obtain the estimated position differential Wherein, the current time t is a positive integer.

9. The method for detecting the speed of a vehicle-mounted permanent magnet synchronous motor according to claim 7 or 8, characterized in that, The voltage-controlled oscillator performs integration processing based on the estimated position derivative to obtain the estimated position signal at the current moment, including: The voltage-controlled oscillator is based on the estimated position signal from the previous time t-1. The estimated position differential Formula used: Obtain the estimated position signal at the current time.

10. The method for detecting the speed of a vehicle-mounted permanent magnet synchronous motor according to claim 9, characterized in that, The method further includes: The voltage-controlled oscillator uses the following formula: The estimated position signal at the current time Perform correction processing to obtain the corrected estimated position signal. The phase detector then uses the measured position signal θ(t) and the corrected estimated position signal... Formula used: Obtain the phase difference ε(t).

11. The method for detecting the speed of a vehicle-mounted permanent magnet synchronous motor according to claim 7, characterized in that, The gain adjustment module acquires the frequency of the measured position signal at the current moment or the rate of change of the measured position signal frequency at the current moment, including: The gain adjustment module adjusts the gain based on the differential of the measured position signal at the current time t. The differential of the measurement position signal at the previous time t-1 at the current time Formula used: Obtain the rate of change of frequency Δf(t) of the measured position signal based on the current time. Wherein, Δt represents the sampling period for acquiring and measuring the position signal.

12. The method for detecting the speed of a vehicle-mounted permanent magnet synchronous motor according to claim 7, characterized in that, The first gain value and the second gain value satisfy: Wherein, ω0 represents the bandwidth of the loop filter, K1 represents the first gain value, K2 represents the second gain value, and ζ represents the transient characteristics in the detection device.

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