Current control loop and motor control system

Abstract

This invention provides a current control loop and motor control system, comprising: a multiplier that multiplies the inductor current by a current sampling ratio to obtain a sampled signal of the inductor current; a first subtractor that calculates the difference between the sampled signal of the inductor current and a reference voltage; a proportional-integral (PI) converter that performs proportional integration on the voltage output of the first subtractor; a divider that divides the output voltage of the PI converter by the amplitude of the sawtooth wave that generates the PWM signal; a second subtractor that calculates the difference between the output voltage of the divider and the output voltage of the voltage loop; and a Laplace transformer that performs a Laplace transform on the output voltage of the second subtractor to adjust the inductor current. The current control loop and motor control system of this invention, through dual voltage and current acquisition of the PWM signal, has advantages such as short PWM sampling time, adjustable PWM duty cycle accuracy, and dynamic matching adjustment of the system.

Description

Technical Field

[0001] This invention relates to the field of motor control, and in particular to a current control loop and a motor control system. Background Technology

[0002] In PWM motor control, the motor operating current signal is typically controlled by turning the switches in the PWM control inverter on or off. For example... Figure 1 As shown, in the motor drive system 1, the microcontroller unit 11 generates a PWM waveform, which drives the motor 13 through the drive module 12. At the same time, the U-phase current IU and V-phase current IV are collected through resistors Ra and Rb respectively (since the sum of the three-phase currents is zero, only two phases need to be collected, and the third phase can be calculated). The sampled current signals are output to the ADC sampling terminal of the microcontroller unit 11 through the built-in operational amplifier and compared with the current of the algorithm. The three-phase current is calculated and the PWM duty cycle is adjusted to control the motor 13.

[0003] The above control method has the following problems: 1. Long PWM sampling time. The switching frequency of power devices in motor control systems is generally between 8kHz and 20kHz. Taking 8kHz as an example, one period of the PWM signal is 125µs. As the switching frequency gradually increases, the period of the PWM signal also becomes shorter. This leads to insufficient sampling time for the MCU's ADC. Currently, more and more motors are high-speed motors, which have fewer pole pairs and very high switching frequencies. The period of the PWM signal is very short. If the ADC sampling time is much longer than the PWM signal period, it will cause serious deviation in ADC sampling, and inaccurate sampling will cause significant problems for motor operation. 2. Low PWM duty cycle adjustment accuracy. Due to the long PWM signal time, the calculation time is also long, resulting in low PWM duty cycle adjustment accuracy. Furthermore, due to the low PWM duty cycle adjustment accuracy, there will be large fluctuations in motor control. 3. The PWM duty cycle cannot be dynamically adjusted.

[0004] Therefore, how to solve the problems of PWM duty cycle not being able to be dynamically adjusted and long sampling time in motor control has become one of the urgent problems to be solved by those skilled in the art.

[0005] It should be noted that the above description of the technical background is only for the purpose of providing a clear and complete explanation of the technical solutions of the present invention and facilitating understanding by those skilled in the art. It should not be assumed that the above technical solutions are known to those skilled in the art simply because they have been described in the background section of this invention. Summary of the Invention

[0006] In view of the shortcomings of the prior art described above, the purpose of this invention is to provide a current control loop and a motor control system to solve the problems of long PWM sampling time, low PWM duty cycle adjustment accuracy, and inability to dynamically adjust PWM duty cycle in the prior art motor control.

[0007] To achieve the above and other related objectives, the present invention provides a current control loop, the current control loop comprising at least:

[0008] The system consists of a first subtractor, a proportional-integral converter, a divider, a second subtractor, a Laplace transform, and a multiplier; among which,

[0009] The multiplier multiplies the inductor current by the current sampling ratio to obtain the sampled signal of the inductor current.

[0010] The first subtractor is connected to the output of the multiplier and is used to calculate the difference between the sampled signal of the inductor current and the reference voltage.

[0011] The proportional-integral converter is connected to the output of the first subtractor and performs proportional integration on the voltage output by the first subtractor.

[0012] The divider is connected to the output of the proportional-integral converter and divides the output voltage of the proportional-integral converter by the amplitude of the sawtooth wave that generates the PWM signal.

[0013] The second subtractor is connected to the output terminal of the divider and receives the output voltage of the voltage loop to calculate the difference between the output voltage of the divider and the output voltage of the voltage loop.

[0014] The Laplace converter is connected to the output of the second subtractor and performs a Laplace transformation on the output voltage of the second subtractor to adjust the inductor current.

[0015] Optionally, the proportional integrator is a single-zero-single-pole compensation network.

[0016] Alternatively, the single-zero-single-pole compensation network includes an operational amplifier, a first resistor, a second resistor, and a capacitor;

[0017] The first end of the first resistor is connected to the output of the first subtractor, and the second end is connected to the inverting input of the operational amplifier; the second resistor and the capacitor are connected in series to form a series structure; one end of the series structure is connected to the second end of the first resistor, and the other end is connected to the output of the operational amplifier; the non-inverting input of the operational amplifier is connected to the set target value.

[0018] Alternatively, the transfer function of the single-zero-single-pole compensation network satisfies:

[0019]

[0020] Wherein, R2 is the resistance value of the second resistor, C1 is the capacitance value of the capacitor, and S is the complex frequency of the Laplace transform.

[0021] Alternatively, the open-loop transfer function of the current control loop satisfies:

[0022]

[0023] Where G1(s) is the transfer function of the proportional-integral converter, V S To generate the amplitude of the sawtooth wave of the PWM signal, S is the complex variable of the Laplace transform, L is the inductance of the inductor; K1 is the sampling ratio of the inductor current, 0 < K1 < 1.

[0024] Alternatively, the output voltage of the voltage loop is the result of comparing the inductor voltage acquisition signal with the corresponding reference voltage.

[0025] To achieve the above and other related objectives, the present invention also provides a motor control system, the motor control system comprising at least:

[0026] Motor, phase voltage detection module, comparator, phase current detection module, microcontroller unit and drive module;

[0027] The phase voltage detection module is connected to the drive module and samples the phase voltage of the motor to obtain the phase voltage sampling signal.

[0028] The comparator is connected to the output of the phase voltage detection module. It compares the sampled phase voltage signal with the corresponding phase reference voltage to obtain the corresponding comparison result, which is then used as the output voltage of the corresponding phase voltage loop.

[0029] The phase current detection module samples the inductor current of each phase of the motor to obtain the current sampling signal of each phase.

[0030] The control unit is connected to the output of the comparator and the phase current detection module, and generates control signals for each phase current based on the current control loop described above.

[0031] The drive module drives the motor to operate based on the output signal of the control unit.

[0032] Optionally, the phase current detection module includes an analog-to-digital converter and three current transformers;

[0033] Each current transformer is applied to the leads of the three-phase inductor of the motor to collect the current on each phase inductor;

[0034] The analog-to-digital converter is connected to the output terminal of each current transformer and is used to convert the analog signals of each phase into digital signals.

[0035] Optionally, the drive module includes a drive control unit and a three-phase full-bridge inverter circuit; the phase voltage detection module includes a third resistor, a fourth resistor, and a fifth resistor.

[0036] The first end of the third resistor is connected to the source of the lower transistor of the first phase in the three-phase full-bridge inverter circuit, and the second end is connected to the source of the lower transistor of the third phase in the three-phase full-bridge inverter circuit; the second end of the third resistor is grounded through the fourth resistor; the source of the lower transistor of the second phase in the three-phase full-bridge inverter circuit is connected to the second end of the third resistor through the fifth resistor.

[0037] Optionally, the control unit is provided with three sets of current control loops.

[0038] As described above, the current control loop and motor control system of the present invention have the following beneficial effects:

[0039] Therefore, in order to improve the accuracy of PWM duty cycle adjustment, this paper proposes a novel PWM duty cycle acquisition method:

[0040] 1. The current control loop and motor control system of the present invention use a current transformer to collect current signals into the control unit, and then use the PWM duty cycle adjustment algorithm inside the control unit to adjust the PWM duty cycle.

[0041] 2. The current control loop and motor control system of the present invention collect voltage signals while collecting current, thereby reducing the amount of calculation. This can ensure the stability of motor speed and reduce the adjustment time of PWM duty cycle.

[0042] 3. The current control loop and motor control system of the present invention have high PWM duty cycle control accuracy, which can meet the requirements of current sampling accuracy during motor operation. Attached Figure Description

[0043] Figure 1 This is a schematic diagram of a motor drive system.

[0044] Figure 2 The diagram shown is a block diagram of the current control loop of the present invention.

[0045] Figure 3 The diagram shown is a schematic representation of the proportional-integral converter of the present invention.

[0046] Figure 4 , Figure 5 The diagram shown is a Bode plot of the present invention.

[0047] Figure 6The diagram shown is a structural schematic of the motor control system of the present invention.

[0048] Component designation explanation

[0049] 1. Motor drive system

[0050] 11 Microcontroller Unit

[0051] 12 Driver Modules

[0052] 13 motors

[0053] 2 Current control loop

[0054] 21 Multipliers

[0055] 22 First Subtractor

[0056] 23 Proportional Integrator

[0057] 231 Operational Amplifier

[0058] 24 Divider

[0059] 25 Second Subtractor

[0060] 26. Laplace Transformer

[0061] 3. Motor Control System

[0062] 31 motor

[0063] 32-phase voltage detection module

[0064] 33 Comparator

[0065] 34-phase current detection module

[0066] 341 Analog-to-Digital Converter

[0067] 35 Control Unit

[0068] 36 Driver Modules

[0069] 361 Drive Control Unit

[0070] 362 Three-phase full-bridge inverter circuit Detailed Implementation

[0071] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

[0072] Please see Figures 2-6 It should be noted that the illustrations provided in this embodiment are only schematic representations of the basic concept of the present invention. Therefore, the drawings only show the components related to the present invention and are not drawn according to the actual number, shape and size of the components in the actual implementation. In the actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.

[0073] like Figure 2 As shown, the present invention provides a current control loop 2, which includes:

[0074] Multiplier 21, first subtractor 22, proportional-integral converter 23, divider 24, second subtractor 25, and Laplace converter 26.

[0075] like Figure 2 As shown, multiplier 21 multiplies the inductor current IL by the current sampling ratio K1 to obtain the sampled signal of the inductor current IL.

[0076] Specifically, the inductor current IL is sampled at a certain ratio and used as a feedback signal. The current sampling ratio K1 is the ratio of the sampled signal to the actual signal, i.e., 0 < K1 < 1. For example, K1 = 1 / 5, 1 / 10, 1 / 20, 1 / 50, 1 / 100, 1 / 150, 1 / 200, which will not be elaborated here.

[0077] like Figure 2 As shown, the first subtractor 22 is connected to the output of the multiplier 21 and is used to calculate the difference between the sampled signal of the inductor current IL and the reference voltage Vcv.

[0078] Specifically, the reference voltage Vcv is a system-given voltage, which can be set according to actual conditions and is not limited here. In this embodiment, the reference voltage Vcv is connected to the non-inverting input terminal of the first subtractor 22, and the output terminal of the multiplier 21 is connected to the inverting input terminal of the first subtractor 22. In actual use, the relative relationship between the input signal and the polarity of the input terminal can be set as needed and is not limited to this embodiment.

[0079] like Figure 2 As shown, the proportional-integral unit 23 is connected to the output terminal of the first subtractor 22 and performs proportional integration on the voltage output by the first subtractor 22.

[0080] Specifically, in this embodiment, the proportional-integral converter 23 is configured as a single-zero-single-pole compensation network. As an example, such as... Figure 3As shown, the single-zero-single-pole compensation network includes an operational amplifier 231, a first resistor R1, a second resistor R2, and a capacitor C1. The first end of the first resistor R1 is connected to the output of the first subtractor 22 (serving as the input IN of the proportional-integral unit 23), and the second end is connected to the inverting input of the operational amplifier 231. The second resistor R2 and capacitor C1 are connected in series to form a series structure; one end of the series structure is connected to the second end of the first resistor R1 (i.e., the inverting input of the operational amplifier 231), and the other end is connected to the output of the operational amplifier 231. In this example, one end of the second resistor R2 is connected to the second end of the first resistor R1, and the other end is connected to the output of the operational amplifier 231 via capacitor C1; their positions can be interchanged. The non-inverting input of the operational amplifier 231 is connected to a target value Ref (set based on actual needs).

[0081] Specifically, since the system's switching frequency is 100kHz, to avoid the influence of the switching frequency on the control loop, the crossover frequency fci must be much smaller than the switching frequency. Of course, for faster system dynamic response, a larger crossover frequency fci is better. Typically, in switching power supplies, the crossover frequency fci is less than 1 / 10 of the switching frequency. In this embodiment, the crossover frequency fci is set to 1 / 10 of the switching frequency; therefore, 10kHz... Z The transfer function of the compensation network satisfies:

[0082]

[0083] Where R2 is the resistance of the second resistor, C1 is the capacitance, and S is the complex frequency of the Laplace transform.

[0084] It should be noted that the single zero-pole compensation network structure is not limited to the examples listed in this embodiment, and will not be elaborated on here.

[0085] like Figure 2 As shown, divider 24 is connected to the output of proportional-integral 23 and divides the output voltage of proportional-integral 23 by the amplitude Vs of the sawtooth wave that generates the PWM signal.

[0086] Specifically, the PWM signal is used to control the power switching transistors in the inverter, and the sawtooth wave serves as the carrier wave of the PWM signal; the output voltage Vd of the divider 24 is the voltage amplitude of the DC wave acquired by the PWM wave.

[0087] like Figure 2 As shown, the second subtractor 25 is connected to the output terminal of the divider 24 and receives the output voltage Vo of the voltage loop, and calculates the difference between the divider output voltage Vd and the voltage loop output voltage Vo.

[0088] Specifically, in this embodiment, the output voltage Vo of the voltage loop is the comparison result of the collected inductor voltage and the corresponding reference voltage. In actual use, the structure of the voltage loop can be set according to actual needs. When the inductor voltage acquisition signal is consistent with the reference voltage, the current control loop 2 does not adjust the inductor current; when the inductor voltage acquisition signal is inconsistent with the reference voltage, the current control loop 2 adjusts the inductor current based on the feedback signal. This invention does not require a large number of external components, directly obtains the voltage loop output voltage Vo through comparison, and does not require calculation of the PWM duty cycle, resulting in low computational load and high speed (short adjustment time for the PWM duty cycle).

[0089] Specifically, in this embodiment, the output terminal of the divider 24 is connected to the non-inverting input terminal of the second subtractor 25, and the output terminal of the voltage loop is connected to the inverting input terminal of the second subtractor 25. In actual use, the relative relationship between the input signal and the polarity of the input terminal can be set as needed, and is not limited to this embodiment.

[0090] like Figure 2 As shown, the Laplace converter 26 is connected to the output of the second subtractor 25 and performs a Laplace transformation on the output voltage of the second subtractor 25 to adjust the inductor current IL.

[0091] Specifically, in motor control, the Laplace transform is mainly used for system analysis and design; through the Laplace transform, the system description in the time domain can be converted into a description in the complex frequency domain, thereby simplifying the analysis and design process. In this invention, the Laplace transform 26 controls the inductor current IL based on the output voltage of the second subtractor 25.

[0092] like Figure 2 As shown in the system block diagram, the open-loop transfer function of the current control loop 2 of this invention satisfies:

[0093]

[0094] Where G1(s) is the transfer function of proportional-integral converter 23, V S To generate the amplitude of the sawtooth wave of the PWM signal, S is the complex variable of the Laplace transform, L is the inductance of the inductor, and K1 is the sampling ratio of the inductor current. Substituting equation (1) into equation (2), then,

[0095] Substituting Vs = 5V, L = 15uH, K1 = 1 / 100, and S = jw into equation (3) above, when fci = 10KHz, |G2(S)| = 1. Let the compensation zero-point angular frequency be... The calculated value is R1C1 = 2.7 × 10⁻⁶. -6 R2C1=2×10 -4 ,so Let R1 = 1K, then we get R2 = 74K and C1 = 2.7nf. Substituting these values ​​into the open-loop transfer function (3), we obtain: The drawn Bird diagram is as follows Figure 4 and Figure 5 As shown, at the (1 / 2)fci frequency, the slope of the open-loop transfer function changes from -40dB to -20dB, achieving a faster dynamic response. Since the transfer function crosses the 0dB line with a slope of -20dB, sufficient phase margin (64 degrees) is also obtained. Simultaneously, because the open-loop transfer function decays with a slope of -40dB from 0Hz to (1 / 2)fci, a very high static gain is achieved, resulting in a very small static error. According to the Nyquist loop stability criterion, the current control loop 2 of this invention is stable and its design is reasonable.

[0096] like Figure 6 As shown, the present invention also provides a motor control system 3, which includes:

[0097] Motor 31, phase voltage detection module 32, comparator 33, phase current detection module 34, control unit 35, and drive module 36.

[0098] like Figure 6 As shown, the drive module 36 drives the motor 31 to operate based on the output signal of the control unit 35.

[0099] Specifically, in this embodiment, the motor 31 is a three-phase motor. The drive module 36 includes a drive control unit 361 and a three-phase full-bridge inverter circuit 362. The drive control unit 361 is implemented using a driver IC; the three-phase full-bridge inverter circuit 362 includes six power switches Q1, Q2, Q3, Q4, Q5, and Q6. Power switches Q1 and Q4 form one totem-pole structure, power switches Q2 and Q5 form another totem-pole structure, and power switches Q3 and Q6 form yet another totem-pole structure. In this example, each power switch is implemented using NMOS transistors. In actual use, appropriate devices can be selected as needed, and this embodiment is not the limitation.

[0100] like Figure 6 As shown, the phase voltage detection module 32 is connected to the drive module 36 to sample the phase voltage of the motor 31 and obtain the phase voltage sampling signal.

[0101] Specifically, in this embodiment, the phase voltage detection module 32 includes a third resistor R3, a fourth resistor R4, and a fifth resistor R5. The first end of the third resistor R3 is connected to the source of the first phase lower transistor Q4 in the three-phase full-bridge inverter circuit 362, and the second end is connected to the source of the third phase lower transistor Q6 in the three-phase full-bridge inverter circuit 362. The second end of the third resistor R3 is grounded via the fourth resistor R4. The source of the second phase lower transistor Q5 in the three-phase full-bridge inverter circuit 362 is connected to the second end of the third resistor R3 via the fifth resistor R5. In practical use, any structure capable of detecting three-phase voltage is applicable to this invention.

[0102] like Figure 6 As shown, comparator 33 is connected to the output terminal of phase voltage detection module 32. It compares the sampled phase voltage signal with the corresponding phase reference voltage to obtain the corresponding comparison result, which is used as the output voltage of the corresponding phase voltage loop.

[0103] Specifically, in this embodiment, the comparator 33 includes three comparison units, which are used to compare each phase voltage with the corresponding reference voltage.

[0104] like Figure 6 As shown, the phase current detection module 34 samples the inductor current of each phase of the motor 31 to obtain the current sampling signal of each phase.

[0105] Specifically, in this embodiment, the phase current detection module 34 includes an analog-to-digital converter 341 and three current transformers (referred to as the first current transformer CT1, the second current transformer CT2, and the third current transformer CT3, respectively); each current transformer is applied to the leads of the three-phase inductors of the motor 31 to collect the current on each phase inductor; the analog-to-digital converter 341 is connected to the output terminal of each current transformer to convert the analog signals of each phase into digital signals.

[0106] It should be noted that when the control unit 35 is equipped with an analog-to-digital conversion unit, the analog-to-digital converter 341 does not need to be configured.

[0107] like Figure 6 As shown, the control unit 35 is connected to the output terminals of the comparator 33 and the phase current detection module 34, and generates control signals for each phase current based on the current control loop 2.

[0108] Specifically, in this embodiment, the control unit 35 is provided with three sets of current control loops 2, each corresponding to a phase current; that is, the first current control loop 2 adjusts the U-phase current based on the comparison result of the U-phase current sampling signal and the U-phase voltage, the second current control loop 2 adjusts the V-phase current based on the comparison result of the V-phase current sampling signal and the V-phase voltage, and the third current control loop 2 adjusts the W-phase current based on the comparison result of the W-phase current sampling signal and the W-phase voltage.

[0109] Specifically, as an example, the control unit 35 is implemented using an MCU.

[0110] like Figures 2-6 As shown, comparator 33 collects the voltages of the U, V, and W phases of the motor, compares them, and transmits the data to control unit 35. Control unit 35 only needs to determine whether to adjust current control loop 2, reducing the computational load on control unit 35. Current transformers collect the currents of the U, V, and W phases respectively. Through the precise acquisition by current transformers and the calculation by operational amplifiers, the data is input to control unit 35 for calculation, realizing dynamic adjustment of the PWM duty cycle. This invention collects voltages simultaneously with current, improving the dynamic parameter adjustment of the motor system, enabling the motor to achieve steady-state operation, and reducing the adjustment time of the PWM duty cycle.

[0111] This invention can dynamically adjust the PWM duty cycle, has a simple structure, low cost, and good control effect; moreover, it has no requirements for the motor, making it convenient and quick to use. Simulation verification shows that this invention operates well.

[0112] In summary, this invention provides a current control loop and a motor control system, comprising: a first subtractor, a proportional-integral (PI) converter, a divider, a second subtractor, a Laplace converter, and a multiplier; wherein, the multiplier multiplies the inductor current by a current sampling ratio to obtain a sampled signal of the inductor current; the first subtractor is connected to the output of the multiplier and is used to calculate the difference between the sampled signal of the inductor current and a reference voltage; the PI converter is connected to the output of the first subtractor and performs proportional integration on the voltage output by the first subtractor; the divider is connected to the output of the PI converter and divides the output voltage of the PI converter by the amplitude of the sawtooth wave that generates the PWM signal; the second subtractor is connected to the output of the divider and receives the output voltage of the voltage loop, calculating the difference between the output voltage of the divider and the output voltage of the voltage loop; the Laplace converter is connected to the output of the second subtractor and performs a Laplace transform on the output voltage of the second subtractor to adjust the inductor current. The current control loop and motor control system of this invention, through dual acquisition of voltage and current of PWM signals, have advantages such as short PWM sampling time, adjustable PWM duty cycle accuracy, and dynamic matching and adjustment of the system. Therefore, this invention effectively overcomes the various shortcomings of the prior art and has high industrial application value.

[0113] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A current control loop, characterized in that, The current control loop includes at least: The system comprises a first subtractor, a proportional-integral converter, a divider, a second subtractor, a Laplace transform, and a multiplier; wherein the multiplier multiplies the inductor current by the current sampling ratio to obtain the sampled signal of the inductor current. The first subtractor is connected to the output of the multiplier and is used to calculate the difference between the sampled signal of the inductor current and the reference voltage. The proportional-integral converter is connected to the output of the first subtractor and performs proportional integration on the voltage output by the first subtractor. The divider is connected to the output of the proportional-integral converter and divides the output voltage of the proportional-integral converter by the amplitude of the sawtooth wave that generates the PWM signal. The second subtractor is connected to the output terminal of the divider and receives the output voltage of the voltage loop to calculate the difference between the output voltage of the divider and the output voltage of the voltage loop. The Laplace converter is connected to the output of the second subtractor and performs a Laplace transformation on the output voltage of the second subtractor to adjust the inductor current.

2. The current control loop according to claim 1, characterized in that: The proportional integrator is a single-zero-single-pole compensation network.

3. The current control loop according to claim 2, characterized in that: The single-zero-single-pole compensation network includes an operational amplifier, a first resistor, a second resistor, and a capacitor; The first end of the first resistor is connected to the output of the first subtractor, and the second end is connected to the inverting input of the operational amplifier; the second resistor and the capacitor are connected in series to form a series structure; one end of the series structure is connected to the second end of the first resistor, and the other end is connected to the output of the operational amplifier; the non-inverting input of the operational amplifier is connected to the set target value.

4. The current control loop according to claim 3, characterized in that: The transfer function of the single-zero-single-pole compensation network satisfies: Wherein, R2 is the resistance value of the second resistor, C1 is the capacitance value of the capacitor, and S is the complex frequency of the Laplace transform.

5. The current control loop according to any one of claims 1-4, characterized in that: The open-loop transfer function of the current control loop satisfies: Where G1(s) is the transfer function of the proportional-integral converter, V S To generate the amplitude of the sawtooth wave of the PWM signal, S is the complex variable of the Laplace transform, L is the inductance of the inductor; K1 is the sampling ratio of the inductor current, 0 < K1 < 1.

6. The current control loop according to any one of claims 1-4, characterized in that: The output voltage of the voltage loop is the result of comparing the inductor voltage acquisition signal with the corresponding reference voltage.

7. A motor control system, characterized in that, The motor control system includes at least: Motor, phase voltage detection module, comparator, phase current detection module, microcontroller unit and drive module; The phase voltage detection module is connected to the drive module and samples the phase voltage of the motor to obtain the phase voltage sampling signal. The comparator is connected to the output of the phase voltage detection module. It compares the sampled phase voltage signal with the corresponding phase reference voltage to obtain the corresponding comparison result, which is then used as the output voltage of the corresponding phase voltage loop. The phase current detection module samples the inductor current of each phase of the motor to obtain the current sampling signal of each phase. The control unit is connected to the output of the comparator and the phase current detection module, and generates control signals for each phase current based on the current control loop as described in any one of claims 1-6. The drive module drives the motor to operate based on the output signal of the control unit.

8. The motor control system according to claim 7, characterized in that: The phase current detection module includes an analog-to-digital converter and three current transformers. Each current transformer is applied to the leads of the three-phase inductor of the motor to collect the current on each phase inductor; The analog-to-digital converter is connected to the output terminal of each current transformer and is used to convert the analog signals of each phase into digital signals.

9. The motor control system according to claim 7, characterized in that: The drive module includes a drive control unit and a three-phase full-bridge inverter circuit; the phase voltage detection module includes a third resistor, a fourth resistor, and a fifth resistor; The first end of the third resistor is connected to the source of the lower transistor of the first phase in the three-phase full-bridge inverter circuit, and the second end is connected to the source of the lower transistor of the third phase in the three-phase full-bridge inverter circuit; the second end of the third resistor is grounded through the fourth resistor; the source of the lower transistor of the second phase in the three-phase full-bridge inverter circuit is connected to the second end of the third resistor through the fifth resistor.

10. The motor control system according to claim 7, characterized in that: The control unit is equipped with three sets of current control loops.

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