PI / PID controller desaturation circuit and PI / PID controller circuit with desaturation function

Abstract

The invention belongs to the technical field of PI / PID control, and particularly relates to a PI / PID controller desaturation circuit and a PI / PID controller circuit with a desaturation function. The desaturation circuit comprises a comparator and a desaturation branch, the desaturation branch is used for being connected with the integrating capacitor in parallel, and a switching tube is connected to the desaturation branch in series; one input end of the comparator is used for being connected with a node capable of representing the difference polarity of a sampling signal and an instruction signal input by the PI / PID controller circuit in the PI / PID controller circuit, the output end of the comparator is connected with the control end of the switching tube, and the comparator outputs a signal according to the signal polarity of the node. Therefore, the switch tube is switched on when the signal polarity of the node is changed by combining the signal of the control end and the voltage condition at the two ends of the integrating capacitor. According to the invention, under the condition that the size relation between the sampling value and the instruction value jumps, the desaturation branch discharges the integrating capacitor, so that the integral item can be desaturated in time.

Description

Technical Field

[0001] The invention belongs to the technical field of PI / PID control, and in particular relates to a PI / PID controller desaturation circuit and a PI / PID controller circuit with a desaturation function. Background Art

[0002] PI / PID controllers are widely used in various occasions. For example, PI controllers are often used in motor drive applications. In this case, there are typical control loops such as current control, speed control, and position control. Current control is the inner loop, and its performance directly determines the overall control performance of the system. At present, current control mainly uses PI controllers, which can meet the needs in most occasions. However, when the magnitude relationship between the current sampling value and the command value changes frequently, the control performance of the conventional PI controller will decline. One of the important reasons for the performance decline is that the integral term in the conventional PI controller cannot be desaturated in time or the desaturation speed is too slow.

[0003] The Chinese utility model patent with the authorization announcement number CN206224280U and the authorization announcement date 2017.06.06 discloses a PI adjustment circuit. In order to prevent the integral capacitor C2 from saturating, an analog switch U3 is connected across the two ends of the capacitor C2, and the analog switch U3 is controlled by the external control signal PI_CTRL signal. When the analog switch U3 is closed, the integral capacitor C2 is short-circuited, and the entire circuit is a pure proportional link without an integral effect. That is, it controls the opening or closing of the analog switch to control the working state of the integral link, avoiding saturation when the control loop stops working, thereby causing the problem of inaccurate output results. The solution of this patent is to directly shield the integral link when the integral is saturated, and only the proportional link works. When the size relationship between the sampling value and the instruction value changes, if only the proportional link works directly, then the steady-state error in the system cannot be eliminated, and the system output cannot be guaranteed to be stable at the expected value. Summary of the invention

[0004] The purpose of the present invention is to provide a PI / PID controller desaturation circuit and a PI / PID controller circuit with a desaturation function, so as to solve the problem that the system output cannot be guaranteed to be stable at an expected value due to directly shielding the integral link in the PI / PID controller when the size relationship between the sampling value and the instruction value changes.

[0005] To solve the above technical problems, the present invention provides a PI / PID controller desaturation circuit, comprising a comparator and a desaturation branch for discharging an integral capacitor in the PI / PID controller circuit, the desaturation branch being connected in parallel with the integral capacitor, and a switch tube being connected in series on the desaturation branch; one of the input ends of the comparator being used to connect a node in the PI / PID controller circuit that can characterize the polarity of the difference between a sampling signal and an instruction signal input to the PI / PID controller circuit, the output end of the comparator being connected to a control end of the switch tube, and the comparator being used to output a signal according to the signal polarity of the node, so that the switch tube is turned on when the signal polarity of the node changes in combination with the signal at the control end and the voltage at both ends of the integral capacitor.

[0006] Furthermore, there are two desaturation branches, and the two desaturation branches are connected in parallel. There are two switch tubes, and the two switch tubes are respectively connected in series to the two desaturation branches; one of the switch tubes is used to turn on when the signal polarity of the node changes from positive to negative, and the other switch tube is used to turn on when the signal polarity of the node changes from negative to positive.

[0007] Furthermore, the node is an output position of a proportional operation in a PI / PID controller circuit.

[0008] Furthermore, the desaturation circuit also includes a voltage stabilizing branch, which is used to be connected in parallel with the integrating capacitor, and a voltage stabilizing tube and a voltage stabilizing resistor are connected in series on the voltage stabilizing branch.

[0009] Furthermore, both switch tubes are triodes, one is an NPN triode and the other is a PNP triode.

[0010] Furthermore, one of the input terminals of the comparator is a non-inverting input terminal of the comparator, and an inverting input terminal of the comparator is grounded.

[0011] The above is a pioneering invention with the following beneficial effects: the present invention designs a PI / PID controller desaturation circuit, in which a comparator and a desaturation branch are provided, wherein one of the input ends of the comparator is used to connect a node in the PI / PID controller circuit that can characterize the difference polarity between a sampling signal and a command signal input to the PI / PID controller circuit, so that the output signal of the comparator is determined by the difference polarity between the sampling signal and the command signal, and the conduction and shutdown of the switch tube in series on the desaturation branch are determined by the comparator output and the voltage across the capacitor. In the face of the situation where the magnitude relationship between the sampling value and the command value frequently jumps, when the polarity of the difference between the sampling value and the command value changes, since the voltage across the integral capacitor still reflects the same situation before the polarity of the difference changes, that is, the voltage across the switch tube still reflects the same situation before the polarity of the difference changes, and then the signal output by the comparator to the control end of the switch tube can turn on the switch tube, and the desaturation branch can adaptively discharge the integral capacitor according to the circuit state. This is an autonomous control method, which realizes that the integral term in the PI / PID controller can be desaturated in time, improves the desaturation speed, and ensures that the PI / PID controller can work stably and reliably. In addition, the cost of the entire circuit is low, so that the PI / PID controller using the desaturation circuit has high working reliability and good operating characteristics, ensuring that the system used by the PI / PID controller can be stable at the expected value.

[0012] In order to solve the above technical problems, the present invention also provides a PI / PID controller circuit with a desaturation function, including a PI / PID controller main circuit, the PI / PID controller main circuit including an integral capacitor, the PI / PID controller circuit also including a PI / PID controller desaturation circuit, the PI / PID controller desaturation circuit including a comparator and a desaturation branch for discharging the integral capacitor, the desaturation branch is connected in parallel with the integral capacitor, and a switch tube is connected in series on the desaturation branch; one of the input ends of the comparator is connected to a node in the PI / PID controller circuit that can characterize the difference polarity of a sampling signal and an instruction signal input to the PI / PID controller circuit, the output end of the comparator is connected to the control end of the switch tube, and the comparator is used to output a signal according to the signal polarity of the node, so that the switch tube is turned on when the signal polarity of the node changes in combination with the signal at the control end and the voltage at both ends of the integral capacitor.

[0013] Furthermore, there are two desaturation branches, and the two desaturation branches are connected in parallel. There are two switch tubes, and the two switch tubes are respectively connected in series to the two desaturation branches; one of the switch tubes is used to turn on when the signal polarity of the node changes from positive to negative, and the other switch tube is used to turn on when the signal polarity of the node changes from negative to positive.

[0014] Furthermore, the node is an output position of a proportional operation in a PI / PID controller circuit.

[0015] Furthermore, the desaturation circuit also includes a voltage stabilizing branch, which is connected in parallel with the integrating capacitor, and a voltage stabilizing tube and a voltage stabilizing resistor are connected in series on the voltage stabilizing branch.

[0016] The above is an improved invention, and the beneficial effect is as follows: the PI / PID controller circuit with desaturation function of the present invention is different from the conventional PI / PID controller circuit, and is a PI / PID controller circuit with the PI / PID controller desaturation circuit designed by the present invention added. The PI / PID controller desaturation circuit is provided with a comparator and a desaturation branch, wherein one of the input ends of the comparator is used to connect to a node in the PI / PID controller circuit that can characterize the difference polarity of the sampling signal and the command signal input to the PI / PID controller circuit, so that the output signal of the comparator is determined by the difference polarity of the sampling signal and the command signal, and the conduction and shutdown of the switch tube connected in series on the desaturation branch are determined by the comparator output and the voltage condition at both ends of the capacitor. In the face of the situation where the size relationship between the sampled value and the command value frequently jumps, when the polarity of the difference between the sampled value and the command value changes, the voltage across the integral capacitor still reflects the same situation as before the polarity of the difference changes, that is, the voltage across the switch tube still reflects the same situation as before the polarity of the difference changes, and then the signal output by the comparator to the control end of the switch tube can turn on the switch tube, and the desaturation branch can adaptively discharge the integral capacitor according to the circuit state. This is an autonomous control method, which realizes that the integral term in the PI / PID controller can be desaturated in time, improves the desaturation speed, and ensures that the PI / PID controller can work stably and reliably. In addition, the cost of the entire circuit is low, which makes the working reliability of the entire PI / PID controller higher and the operating characteristics better, ensuring that the system used by the PI / PID controller can be stable at the expected value. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 is a circuit diagram of a PI controller main body circuit in the PI controller circuit of the present invention; Figure 2 is a circuit diagram of a PI controller circuit of the present invention. DETAILED DESCRIPTION

[0018] The present invention designs a PI / PID controller desaturation circuit, which includes a comparator and a desaturation branch, the desaturation branch is connected in parallel with the integral capacitor in the PI / PID controller circuit, and a switch tube is connected in series on the desaturation branch. One of the input ends of the comparator is used to connect a node in the PI / PID controller circuit that can characterize the difference polarity of the sampling signal and the command signal input by the PI / PID controller circuit, the output end of the comparator is connected to the control end of the switch tube, and the comparator is used to output a signal according to the signal polarity of the node, so that the switch tube is turned on when the signal polarity of the node changes in combination with the signal of the control end and the voltage condition at both ends of the integral capacitor. Thereby, when the magnitude relationship between the sampling value and the command value jumps, the integral capacitor is discharged by the desaturation branch, so that the integral term in the PI / PID controller can be desaturated in time, the desaturation speed is improved, and the PI / PID controller can be ensured to work stably and reliably. Based on this, a PI / PID controller desaturation circuit and a PI / PID controller circuit with a desaturation function of the present invention can be realized.

[0019] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention is further described in detail below with reference to the accompanying drawings and embodiments.

[0020] PI controller circuit embodiment with desaturation function: This embodiment provides a PI controller circuit with a desaturation function, and its circuit diagram is as follows: Figure 2 As shown, it includes a PI controller main circuit and a PI controller desaturation circuit. The PI controller main circuit is as shown in Figure 1 The PI controller circuit can be applied to various occasions. In this embodiment, the application in motor drive is taken as an example for explanation, and the PI controller is a controller used for current control in motor drive control. Therefore, the command and feedback signals of the PI controller are respectively a current command signal and a current sampling signal. The output of the PI controller is a voltage command signal, which can be transmitted to the subsequent circuit to realize closed-loop control of the motor current.

[0021] The circuit diagram of the PI controller main circuit is as follows Figure 1 As shown, it includes an amplifier U1 and an integrator U3. The in-phase input terminal and the inverting input terminal of the amplifier U1 are connected to the sampling signal and the command signal respectively, which are the current sampling signal i and the current command signal i in this embodiment. * , the output of amplifier U1 is K(ii *), which is the output of the proportional operation in the PI controller, where K is the amplification factor of the amplifier U1. The branch between the in-phase input and output of the integrator U3 is connected in series with an integrating capacitor C1 and a resistor R9. The integrating capacitor C1 is used to store charge to realize the integral function of the PI control. The output of the integrator U3 is the output of the entire PI controller circuit.

[0022] The circuit diagram of the PI controller with a PI controller desaturation circuit is as follows: Figure 2 As shown, the PI controller desaturation circuit includes a comparator U2, a desaturation branch and a voltage stabilization branch. There are two desaturation branches and one voltage stabilization branch. The two desaturation branches are used to realize directional discharge of the integral capacitor C1. The two desaturation branches and the voltage stabilization branch are arranged in parallel, and the three branches are all connected in parallel with the integral capacitor C1. The two desaturation branches are both RC charging and discharging branches, one of which is connected in series with a switch tube Q1 and a resistor R6 on the desaturation branch, and the other is connected in series with a switch tube Q2 and a resistor R7 on the desaturation branch. In this embodiment, the switch tube Q1 and the switch tube Q2 are both triodes, and the switch tube Q1 is an NPN triode, and the switch tube Q2 is a PNP triode. The voltage stabilization branch is connected in series with a voltage stabilization tube D1 and a voltage stabilization resistor R8. The voltage stabilization tube D1 is used to limit the voltage of the integral capacitor C1 not to exceed the set value, so as to achieve the limiting of the integral term. The non-inverting input of the comparator U2 is connected to the output of the amplifier U1, the inverting input is grounded, and the output is connected to the control terminals of the switch tube Q1 and the switch tube Q2, which are the bases of the two transistors. The output of the comparator U2 can change the state of the switch tube Q1 and the switch tube Q2 in conjunction with the voltage across the integral capacitor C1, so as to achieve the purpose of discharging the integral capacitor C1 using the resistor R7 or the resistor R6.

[0023] The working principle and process of the above PI controller circuit with a PI controller desaturation circuit are as follows: When the current sampling signal i is less than the current command signal i * When the error polarity (i.e. the positive and negative properties of the error) is negative, the output of the amplifier U1 is negative, causing the output of the integrator U3 to increase continuously, and finally the integral link reaches the limit. At this time, the integral capacitor C1 is high on the right and low on the left (the left and right directions here are Figure 2 In the left and right directions, and in this process, since the output of amplifier U1 is negative, the output of comparator U2 is negative. Since the integral capacitor C1 is in the state of high on the right and low on the left, both NPN transistor Q1 and PNP transistor Q2 are in the off state. If the current sampling signal i suddenly becomes greater than the current command signal i *(It may be caused by load changes). Due to the change in error polarity from negative to positive, the output of amplifier U1 is positive. Although the voltage of integrating capacitor C1 decreases slowly, the output is still large, and the voltage across integrating capacitor C1 is still high on the right and low on the left. Since the output of amplifier U1 is positive, the output of comparator U2 is also positive. Since the voltage across integrating capacitor C1 is still high on the right and low on the left, NPN transistor Q1 is turned on and PNP transistor Q2 remains off. At this time, integrating capacitor C1 will discharge through resistor R6, which accelerates the desaturation process of integrating capacitor C1 and improves dynamic performance.

[0024] When the current sampling signal i is greater than the current command signal i * When the error polarity is positive, the output of amplifier U1 is positive, causing the output of integrator U3 to increase continuously, and finally the integral link reaches the limit. At this time, the integral capacitor C1 is in a state of high on the left and low on the right. In this process, since the output of amplifier U1 is positive, the output of comparator U2 is positive. Since the integral capacitor C1 is in a state of high on the left and low on the right, both NPN transistor Q1 and PNP transistor Q2 are in the off state. If the current sampling signal i suddenly appears to be less than the current command signal i * (It may be caused by load changes). Due to the change in error polarity from positive to negative, the output of amplifier U1 is negative. Although the voltage of integrating capacitor C1 decreases slowly, the output is still large, and the voltage across integrating capacitor C1 is still high on the left and low on the right. Since the output of amplifier U1 is negative, the output of comparator U2 is also negative. Since the voltage across integrating capacitor C1 is still high on the left and low on the right, NPN transistor Q1 remains in the off state and PNP transistor Q2 is turned on. At this time, integrating capacitor C1 will discharge through resistor R7, which accelerates the desaturation process of integrating capacitor C1 and improves dynamic performance.

[0025] Through the introduction of the above circuit structure and working process, it can be known that the focus of the present invention is to set a desaturation branch in parallel at both ends of the integral capacitor C1, a switch tube and a resistor are connected in series on the desaturation branch, the control end of the switch tube is connected to the output end of the comparator U2, and the comparator U2 is used to output a signal according to the difference polarity of the sampling signal and the command signal input by the PI controller circuit, thereby realizing that the switch tube on the desaturation branch can be turned on when the difference polarity changes according to the signal condition of the switch tube control end and the voltage condition at both ends of the integral capacitor, so that the integral capacitor C1 can be discharged through the resistor connected in series on the desaturation branch, thereby accelerating the desaturation process. In order to realize the above scheme, the specific circuit design can be based on Figure 2There are other adjustments: for example, the switch tubes Q1 and Q2 can select other types of power devices besides triodes, such as MOS tubes, and adaptively select n-channel or p-channel MOS tubes; for example, the output end of the amplifier U1 is connected to the inverting input end of the comparator U2, and the non-inverting input end of the comparator U2 is grounded. At this time, it is necessary to adaptively adjust the NPN and PNP types of the switch tubes Q1 and Q2.

[0026] Moreover, when the objects connected to the in-phase input and inverting input of the amplifier U1 in the PI controller main circuit change, that is, the in-phase input of the amplifier U1 is connected to the command signal and the inverting input is connected to the sampling signal, the above-mentioned PI controller desaturation circuit can still be used to implement the desaturation process, but it is necessary to adjust the NPN and PNP types of the switch tubes Q1 and Q2 according to adaptability. In addition, when the circuit structure of the PI controller main circuit changes, the above-mentioned PI controller desaturation circuit can also be used to implement the desaturation process. However, it is required that the in-phase input of the comparator U2 is connected to the node in the PI controller circuit that can characterize the difference polarity between the sampling signal and the command signal input to the PI controller circuit, and the desaturation branch is connected in parallel at both ends of the integral capacitor.

[0027] PI controller desaturation circuit embodiment: The present embodiment provides a PI controller desaturation circuit, which is used to perform directionally discharge on an integral capacitor in the PI controller circuit. The structure, application scenarios, working principle and achievable effects of the PI controller desaturation circuit have been described in detail in the embodiment of the PI controller circuit with a desaturation function, and will not be described in detail in the present embodiment.

[0028] PID controller circuit embodiment with desaturation function: This embodiment provides a PID controller circuit with a desaturation function, and the PID controller circuit includes a PID controller main circuit and a PID controller desaturation circuit. The PID controller main circuit essentially includes three parts: proportional, integral and differential. Considering that it has one more differential part than the PI controller main circuit, the specific circuit of the PID controller main circuit is not given in this embodiment. The basic principle and circuit structure of the PID controller desaturation circuit are the same as those of the PI controller desaturation circuit introduced in the PI controller circuit, except that the desaturation object becomes the integral capacitor in the PID controller main circuit.

[0029] PID controller desaturation circuit embodiment: The present embodiment provides a PID controller desaturation circuit, which is used to perform directionally discharge on an integral capacitor in a PID controller circuit. The structure, application scenarios, working principle and achievable effects of the PID controller desaturation circuit have been described in detail in the embodiment of the PID controller circuit with a desaturation function, and will not be described in detail in the present embodiment.

[0030] In summary, the present invention accelerates the desaturation process of the integral capacitor in the PI / PID controller circuit when the error polarity of the PI / PID controller input signal changes through the designed PI / PID controller desaturation circuit, thereby improving the dynamic performance, and has the advantages of fast calculation speed, low cost, reliable operation, and good operating characteristics.

[0031] Specific implementation methods are given above, but the present invention is not limited to the described implementation methods. The basic idea of ​​the present invention lies in the above basic scheme. For ordinary technicians in this field, it does not take creative work to design various deformed models, formulas, and parameters according to the teachings of the present invention. Changes, modifications, substitutions, and variations of the implementation methods without departing from the principles and spirit of the present invention still fall within the scope of protection of the present invention.

Claims

1. A PI / PID controller desaturation circuit, characterized in that: It includes a comparator and a desaturation branch for discharging an integral capacitor in a PI / PID controller circuit, the desaturation branch is connected in parallel with the integral capacitor, and a switch tube is connected in series on the desaturation branch; One of the input ends of the comparator is used to connect to a node in the PI / PID controller circuit that can characterize the polarity of the difference between the sampling signal and the command signal input to the PI / PID controller circuit. The output end of the comparator is connected to the control end of the switch tube, and the comparator is used to output a signal according to the signal polarity of the node, so that the switch tube is turned on when the signal polarity of the node changes in combination with the signal at the control end and the voltage across the integral capacitor.

2. The PI / PID controller desaturation circuit according to claim 1, characterized in that: There are two desaturation branches, and the two desaturation branches are connected in parallel. There are two switch tubes, and the two switch tubes are respectively connected in series to the two desaturation branches; one of the switch tubes is used to be turned on when the signal polarity of the node changes from positive to negative, and the other switch tube is used to be turned on when the signal polarity of the node changes from negative to positive.

3. The PI / PID controller desaturation circuit according to claim 1, characterized in that: The node is the output position of the proportional operation in the PI / PID controller circuit.

4. The PI / PID controller desaturation circuit according to claim 1, characterized in that: The desaturation circuit also includes a voltage stabilizing branch, which is used to be connected in parallel with the integrating capacitor, and a voltage stabilizing tube and a voltage stabilizing resistor are connected in series on the voltage stabilizing branch.

5. The PI / PID controller desaturation circuit according to claim 2, characterized in that: Both switch tubes are triodes, one is an NPN triode and the other is a PNP triode.

6. The PI / PID controller desaturation circuit according to any one of claims 1 to 5, characterized in that: One of the input terminals of the comparator is a non-inverting input terminal of the comparator, and the inverting input terminal of the comparator is grounded.

7. A PI / PID controller circuit with a desaturation function, comprising a PI / PID controller main circuit, the PI / PID controller main circuit comprising an integral capacitor, the PI / PID controller circuit further comprising a PI / PID controller desaturation circuit, characterized in that: The PI / PID controller desaturation circuit includes a comparator and a desaturation branch for discharging an integral capacitor, the desaturation branch is connected in parallel with the integral capacitor, and a switch tube is connected in series on the desaturation branch; One of the input ends of the comparator is connected to a node in the PI / PID controller circuit that can characterize the polarity of the difference between the sampling signal and the command signal input to the PI / PID controller circuit, the output end of the comparator is connected to the control end of the switch tube, and the comparator is used to output a signal according to the signal polarity of the node, so that the switch tube is turned on when the signal polarity of the node changes in combination with the signal at the control end and the voltage across the integral capacitor.

8. The PI / PID controller circuit with desaturation function according to claim 7, characterized in that: There are two desaturation branches, and the two desaturation branches are connected in parallel. There are two switch tubes, and the two switch tubes are respectively connected in series to the two desaturation branches; one of the switch tubes is used to be turned on when the signal polarity of the node changes from positive to negative, and the other switch tube is used to be turned on when the signal polarity of the node changes from negative to positive.

9. The PI / PID controller circuit with desaturation function according to claim 7, characterized in that: The node is the output position of the proportional operation in the PI / PID controller circuit.

10. The PI / PID controller circuit with desaturation function according to any one of claims 7 to 9, characterized in that: The desaturation circuit also includes a voltage stabilizing branch, which is connected in parallel with the integrating capacitor, and a voltage stabilizing tube and a voltage stabilizing resistor are connected in series on the voltage stabilizing branch.

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