A controller and control method for a five-phase motor

Abstract

The present invention discloses a controller and control method for a five-phase motor, including a power circuit, a control circuit, and an isolation circuit. The power circuit includes a five-phase inverter circuit and a neutral point three-level modulator circuit. The control circuit includes a main control circuit, an angle sensor, and a current sensor. The signal output of the main control circuit is connected to the control signal input of the five-phase inverter circuit and the control signal input of the neutral point three-level modulator circuit via the isolation circuit. The signal input of the main control circuit is connected to the angle sensor of the five-phase motor, and the current sensors of each phase of the five-phase inverter circuit are connected to the signal input of the main control circuit. The present invention reduces current and torque fluctuations in such low-inductance five-phase motors in both healthy and faulty operating conditions, and has the advantages of low cost, high control accuracy, and high fault tolerance.

Description

Technical Field

[0001] The present invention relates to the technical field of motor control, and in particular to a controller and a control method for a five-phase motor. Background Art

[0002] Compared with traditional three-phase motors, five-phase motors have the advantages of high power density, smoother torque and high reliability. High-speed motors have the advantages of high power density, small size and weight, and high working efficiency. Five-phase high-speed motors can combine the above advantages at the same time and have huge application potential in aviation, automobiles, ships and other fields.

[0003] High-speed motors are designed for high speeds and require low motor inductance. Currently, five-phase motor drive control systems mostly use IGBT-based general-purpose inverters, designed for machines with sufficiently high inductance. However, when driving low-inductance motors, general-purpose inverters exhibit poor current control performance, primarily manifesting in large current fluctuations. This results in reduced motor control accuracy and stability.

[0004] To reduce current fluctuations in low-inductance motor drive control, the current main approaches are to increase the system's inductance by adding an external inductor or to increase the switching frequency. The former increases the overall system size and weight due to the external inductor, and also loses the advantages of low-inductance motors, such as fast system response and higher system parameter linearity. The latter requires hardware upgrades and the use of higher-performance power devices with both high breakdown voltage and high switching frequency, as well as a certain current-carrying capacity. Because multi-phase motor drive systems have a large number of power devices, this solution significantly increases the cost of the drive control system.

[0005] For fault-tolerant control, existing research has focused on improving hardware fault tolerance by employing open windings and adding redundant bridge arms. The former requires twice the number of power components as a half-bridge topology, significantly increasing size and cost. While the latter improves fault tolerance, the redundant bridge arms do not need to operate under healthy operating conditions, resulting in a waste of resources.

[0006] In order to overcome these defects, it is necessary to design a controller and control method with small current fluctuation, good fault tolerance, and adaptability to low-inductance motors. Summary of the Invention

[0007] The purpose of the present invention is to overcome the deficiencies of the above-mentioned prior art and provide a controller and control method for a five-phase motor. This circuit topology has a neutral point three-level modulation capability and can increase the control voltage vector frequency by increasing the neutral point voltage frequency, thereby reducing the current fluctuation in the low-inductance motor control. The designed model predictive control strategy optimizes the control set, improving the control accuracy while reducing the computational burden. The control strategy determines the optimal control voltage and duty cycle by minimizing the current fluctuation of the low-inductance motor, thereby improving the control performance of the low-inductance motor. When a phase failure occurs, the basic voltage vector is reconstructed to achieve an improvement in the fault-tolerant control performance. The present invention reduces the current and torque fluctuations of such low-inductance five-phase motors in healthy and faulty conditions, and has the advantages of low cost, high control accuracy, and high fault tolerance.

[0008] In order to achieve the above object, the present invention adopts the following technical solutions:

[0009] A controller for a five-phase motor includes a power circuit, a control circuit, and an isolation circuit. The power circuit includes a five-phase inverter circuit and a neutral point three-level modulator circuit. The control circuit includes a main control circuit, an angle sensor, and a current sensor. The signal output end of the main control circuit is connected to the control signal input end of the five-phase inverter circuit and the control signal input end of the neutral point three-level modulator circuit through the isolation circuit. The signal input end of the main control circuit is connected to the angle sensor of the five-phase motor. The current sensor of each phase of the five-phase inverter circuit is connected to the signal input end of the main control circuit.

[0010] The isolation circuit includes an isolation circuit 1 and an isolation circuit 2, and the isolation circuit 1 and the isolation circuit 2 are circuits with the same structure.

[0011] The angle sensor adopts a rotary transformer.

[0012] The five-phase inverter circuit includes a DC power supply Udc, a capacitor No. 1 C1, a capacitor No. 2 C2, a power switch No. 1 S1, a power switch No. 2 S2, a power switch No. 3 S3, a power switch No. 4 S4, a power switch No. 5 S5, a power switch No. 6 S6, a power switch No. 7 S7, a power switch No. 8 S8, a power switch No. 9 S9 and a power switch No. 10 S10. The power switch No. 1 S1, the power switch No. 3 S3, the power switch No. 5 S5, the power switch No. 6 S6, the power switch No. 7 S7, the power switch No. 8 S8, the power switch No. 9 S9 and the power switch No. 10 S10. The collectors of the power switch devices S5, S7, and S9 are all connected to the positive electrode of the DC power supply Udc. The emitters of the power switch devices S2, S4, S6, S8, and S10 are all connected to the negative electrode of the DC power supply Udc. The emitter of the power switch device S1 and the collector of the power switch device S2 are combined and connected to the U terminal of the current sensor. The A end of the current sensor is connected to the A phase of the five-phase motor, the emitter of the third power switch device S3 and the collector of the fourth power switch device S4 are combined and connected to the V end of the current sensor, the B end of the current sensor is connected to the B phase of the five-phase motor, the emitter of the fifth power switch device S5 and the collector of the sixth power switch device S6 are combined and connected to the W end of the current sensor, the C end of the current sensor is connected to the C phase of the five-phase motor, the emitter of the seventh power switch device S7 and the collector of the eighth power switch device S8 are combined and connected to the X end of the current sensor, the D end of the current sensor is connected to the D phase of the five-phase motor, the emitter of the ninth power switch device S9 and the collector of the tenth power switch device S10 are combined and connected to the Y end of the current sensor, the E end of the current sensor is connected to the E phase of the five-phase motor, one end of the No. 1 capacitor C1 is connected to the positive pole of the DC power supply Udc, one end of the No. 2 capacitor C2 is connected to the negative pole of the DC power supply Udc, and the other ends of the No. 1 capacitor C1 and the No. 2 capacitor C2 are connected.

[0013] The neutral point three-level modulated circuit includes a power switch device No. 11 S11, a power switch device No. 12 S12, a power switch device No. 13 S13, a power switch device No. 14 S14, a single-phase conduction element No. 1 D1 and a single-phase conduction element No. 2 D2. The collector of the power switch device No. 11 S11 is connected to the positive electrode of the DC power supply Udc, the emitter of the power switch device No. 11 S11 is connected to the collector of the power switch device No. 12 S12, the emitter of the power switch device No. 12 S12 is connected to the collector of the power switch device No. 13 S13, the emitter of the power switch device No. 13 S13 is connected to the collector of the power switch device No. 14 S14, and the emitter of the power switch device No. 14 S14 is connected to the collector of the power switch device No. 14 S14. The electrode is connected to the negative electrode of the DC power supply Udc, the emitter of the twelfth power switch device S12 and the collector of the thirteenth power switch device S13 are both connected to the neutral point N of the five-phase motor, the emitter of the eleventh power switch device S11 and the collector of the twelfth power switch device S12 are both connected to the cathode of the first single-phase conduction element D1, the emitter of the thirteenth power switch device S13 and the collector of the fourteenth power switch device S14 are both connected to the anode of the second single-phase conduction element D2, the anode of the first single-phase conduction element D1 is connected to the cathode of the second single-phase conduction element D2, and the anode of the first single-phase conduction element D1 and the cathode of the second single-phase conduction element D2 are both connected to the midpoint of the first capacitor C1 and the second capacitor C2.

[0014] The power switch device No. 1 S1, the power switch device No. 2 S2, the power switch device No. 3 S3, the power switch device No. 4 S4, the power switch device No. 5 S5, the power switch device No. 6 S6, the power switch device No. 7 S7, the power switch device No. 8 S8, the power switch device No. 9 S9, and the power switch device No. 10 S10 are all composed of IGBT and an anti-parallel freewheeling diode D3, and the operating frequency is set to 10kHz; the power switch device No. 11 S11, the power switch device No. 12 S12, the power switch device No. 13 S13, and the power switch device No. 14 S14 use SiC and can operate at high frequency, and the operating frequency is set to 80kHz.

[0015] A five-phase motor control method includes the following steps:

[0016] Acquisition of sensor signals: The current sensor collects the A-phase current signal CURRENT A, the B-phase current signal CURRENT B, the C-phase current signal CURRENT C, the D-phase current signal CURRENT D, the E-phase current signal CURRENT E, and the rotor position signal θ, and calculates the actual speed ω based on the differential of the rotor position signal r ;

[0017] Set target speed

[0018] Determine whether a fault occurs based on the working status of the five-phase motor. If a fault occurs, calculate the maximum speed at the time of the fault. If no fault occurs, calculate the maximum speed at normal operation.

[0019] Compare the current maximum speed and target speed. If the target speed exceeds the maximum speed, set the target speed to the maximum speed and adjust the target current according to the error between the actual speed and the target speed. If the target speed does not exceed the maximum speed, adjust the target current according to the error between the actual speed and the target speed.

[0020] Design a PI controller as a speed controller to obtain the q-axis target current value Set the d-axis target current value is 0;

[0021] Design a model-predictive current control method to calculate the duty cycle of a neutral point three-level modulated circuit;

[0022] The action time of the basic voltage vector is calculated based on the optimal voltage vector, thereby calculating the state and action time of the power switching devices S1-S10. Finally, the main control circuit outputs PWM to control the power switching devices S1-S14;

[0023] If the motor is shut down, the output channel is closed. If the motor is not shut down and continues to run, the sensor signal is collected again and enters the loop.

[0024] Model predictive current control methods include:

[0025] Through coordinate transformation, the five-phase current is transformed into the direct-orthogonal coordinate system, including the actual value of the d-axis current i d and the actual value of the q-axis current i q ;

[0026] Determine whether a fault has occurred based on the working status of the five-phase motor, establish virtual voltage vectors for normal operation and for faults, and construct a control set for model-predictive current control.

[0027] The discrete current prediction model of the five-phase motor is established as follows:

[0028]

[0029] Among them, k is the current calculation cycle, i d (k) is the d-axis current value of k period, i q (k) is the q-axis current value of k period, i d (k+1) is the d-axis predicted current value of the k+1 period, i q(k+1) is the predicted q-axis current value of the k+1 period, u d (k) is the d-axis voltage value of k cycles, u q (k) is the q-axis voltage value of k cycles, T s is the control period, R s is the motor winding resistance, L d is the motor d-axis inductance, L q is the motor q-axis inductance, ψ m is the permanent magnet flux of the motor, ω r is the current actual speed;

[0030] The predicted current model considering duty cycle optimization is established as follows:

[0031]

[0032] in,

[0033] i d (k+2) is the d-axis predicted current value of the k+2 period, i q (k+2) is the predicted q-axis current value of the k+2 period, r i is the duty cycle of the i-th vector in the control set, u di is the d-axis voltage value corresponding to the i-th vector in the control set, u qi is the q-axis voltage value corresponding to the i-th vector in the control set;

[0034] Construct a cost function g based on the d-axis and q-axis current errors i ;

[0035]

[0036] Among them, i d (k+2) is the d-axis predicted current value of the k+2 period, i q (k+2) is the predicted q-axis current value of the k+2 period, and λ is the weight coefficient; is the q-axis target current value, is the d-axis target current value;

[0037] The optimal voltage vector and its duty cycle are obtained by optimizing the cost function;

[0038]

[0039] Among them, v vi is the voltage vector in the control set, v vp is the calculated optimal voltage vector, Represents the ergodic voltage vector v vi Calculate g i , and calculate so that gi smallest vector; Indicates g i to r i The partial derivative of

[0040] Adaptively adjust the optimal voltage and duty cycle, and use the amplitude ratio of the small virtual voltage vector to the large virtual voltage vector as the threshold w;

[0041]

[0042] Among them, V vs is a small virtual voltage vector, V vb is the large virtual voltage vector;

[0043] When the duty cycle of the optimal voltage vector is less than the threshold, the optimal voltage vector is replaced by a small virtual voltage vector in the same direction, and a new duty cycle is calculated;

[0044] r i '=1.618*r i

[0045] Finally, zero-sequence current control is performed, a zero-sequence current prediction model is established, and zero-sequence current control is performed based on the deadbeat method. The zero-sequence current control is set to 0, and the target zero-sequence voltage is calculated.

[0046]

[0047] in, is the target zero-sequence voltage, is the target zero-sequence current value, set to 0, L s is the inductance of the zero-sequence circuit, i0(k+1) is the predicted zero-sequence current value in the k+1 cycle, R s is the motor winding resistance, T s is the control cycle;

[0048] The selected optimal voltage vector can be synthesized from the basic voltage vectors obtained from different neutral point potentials. According to the target zero-sequence voltage, the proportion of the action time of different neutral point potentials can be designed and calculated.

[0049] Normal virtual voltage vector construction method: In the stationary coordinate system, according to the working state of the power switch devices S11-S14, the neutral point potential can be Udc, Udc / 2, 0; according to the working state of the power switch devices S1-S10, the potentials of the U, V, W, X, and Y terminals can be Udc and 0. When the neutral point potentials are Udc, Udc / 2, and 0, 2 can be constructed according to different combinations of the potentials of the U, V, W, X, and Y terminals. 5= 32 basic voltage vectors, and the voltage vector distribution and amplitude in the fundamental space and harmonic space are different. According to the constraint condition that the third harmonic voltage vector is 0, two groups of virtual voltage vectors with different amplitudes are combined into V vi , large virtual voltage vector V vb The small virtual voltage vector V is synthesized by the large basic voltage vector and the medium basic voltage vector. vs Composed of a medium base voltage vector and a small base voltage vector;

[0050] A method for constructing a virtual voltage vector during a fault: when a z-phase short-circuit fault occurs, z=1,2, the duty cycle is set to r, the duty cycle of the neutral point voltage is fixed, and the working mode of the neutral point three-level modulated circuit (2) is divided into two types. One working mode is that within a control cycle, the twelfth power switch device S12 is in the on state, the fourteenth power switch device S14 is in the off state, the states of the eleventh power switch device S11 and the thirteenth power switch device S13 are variable and opposite in state, when the eleventh power switch device S11 is in the on state and the thirteenth power switch device S13 is in the off state, the neutral point potential is Udc, when the eleventh power switch device S11 is in the off state and the thirteenth power switch device S13 is in the off state, the neutral point potential is Udc. When the switch device S13 is in the on state, the neutral point potential is Udc / 2; the other working mode is that within one control cycle, the eleventh power switch device S11 is in the off state, the thirteenth power switch device S13 is in the on state, the states of the twelfth power switch device S12 and the fourteenth power switch device S14 are variable and opposite in state. When the twelfth power switch device S12 is in the on state and the fourteenth power switch device S14 is in the off state, the neutral point potential is Udc / 2, when the twelfth power switch device S12 is in the off state and the fourteenth power switch device S14 is in the on state, the neutral point potential is 0; in the two working modes, 2 can be constructed according to different combinations of the effective phase terminal potentials. (5-z) A basic voltage vector is generated, and a virtual voltage vector is constructed based on the principle of ensuring the amplitude of the fundamental space vector as much as possible while suppressing the harmonic voltage.

[0051] The beneficial effects of the present invention are:

[0052] 1. Adding a three-level modulated neutral point circuit can achieve three adjustable potentials of the neutral point: 0V, Udc / 2, and Udc. This topology increases the control freedom and improves the fault-tolerant control capability of the multi-phase motor.

[0053] Second, increasing the switching frequency in the neutral point adjustable circuit can increase the voltage modulation frequency, thereby reducing the current and torque ripple of the low-inductance motor.

[0054] 3. Two sets of virtual voltage vectors with unequal amplitudes are proposed to suppress harmonic voltages, and a method for selecting the amplitude of virtual voltage vectors is proposed to ensure voltage output capability while improving the current and torque pulsation of low-inductance motors.

[0055] 4. A duty cycle control method for the signal input terminal of the power switching device in the neutral point adjustable circuit is proposed, which can control the zero-sequence current and further reduce the current and torque pulsation.

[0056] 5. A virtual voltage vector reconstruction method and a current control method under fault conditions are proposed to improve the fault-tolerant control performance of the five-phase motor. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] Figure 1 A circuit diagram of a controller for a five-phase motor according to the present invention;

[0058] Figure 2 for Figure 1 Local circuit principle Figure 1 ;

[0059] Figure 3 for Figure 1 Local circuit principle Figure 2 ;

[0060] Figure 4 is a flow chart of the control method of the present invention;

[0061] Figure 5 This is a flow chart of the model prediction current control method of the present invention.

[0062] In the figure: five-phase inverter circuit 1, neutral point three-level modulator circuit 2, main control circuit 3, angle sensor 4, current sensor 5, isolation circuit 1 6, isolation circuit 2 7, five-phase motor 8. DETAILED DESCRIPTION

[0063] The present invention will be further described below with reference to the accompanying drawings and specific embodiments:

[0064] like Figure 1-5 As shown, a controller for a five-phase motor includes a power circuit, a control circuit and an isolation circuit.

[0065] Reference Figure 1 The power circuit includes a five-phase inverter circuit 1 and a neutral point three-level modulator circuit 2. The control circuit includes a main control circuit 3, an angle sensor 4, and a current sensor 5. The isolation circuit includes an isolation circuit 1 6 and an isolation circuit 2 7. These isolation circuits 1 6 and 2 7 have the same structure and utilize an optocoupler isolation module. The angle sensor 4 utilizes a rotary transformer.

[0066] Reference Figure 1 、 Figure 2 The five-phase inverter circuit 1 includes a DC power supply Udc, a capacitor No. 1 C1, a capacitor No. 2 C2, a power switch device No. 1 S1, a power switch device No. 2 S2, a power switch device No. 3 S3, a power switch device No. 4 S4, a power switch device No. 5 S5, a power switch device No. 6 S6, a power switch device No. 7 S7, a power switch device No. 8 S8, a power switch device No. 9 S9 and a power switch device No. 10 S10, wherein the power switch device No. 1 S1, the power switch device No. 3 S3, the power switch device No. 5 S5 The collectors of the seventh power switch device S7 and the ninth power switch device S9 are all connected to the positive electrode of the DC power supply Udc, the emitters of the second power switch device S2, the fourth power switch device S4, the sixth power switch device S6, the eighth power switch device S8, and the tenth power switch device S10 are all connected to the negative electrode of the DC power supply Udc, the emitter of the first power switch device S1 and the collector of the second power switch device S2 are combined and connected to the U end of the current sensor 5, and the (other end) A end of the current sensor 5 is connected to the five-phase Phase A of the motor 8, the emitter of the third power switch device S3 and the collector of the fourth power switch device S4 are combined and connected to the V end of the current sensor 5, the (other end) B end of the current sensor 5 is connected to the B phase of the five-phase motor 8, the emitter of the fifth power switch device S5 and the collector of the sixth power switch device S6 are combined and connected to the W end of the current sensor 5, the (other end) C end of the current sensor 5 is connected to the C phase of the five-phase motor 8, the emitter of the seventh power switch device S7 and the collector of the eighth power switch device S8 are combined and connected to the W end of the current sensor 5, the (other end) C end of the current sensor 5 is connected to the C phase of the five-phase motor 8, After the poles are merged, they are connected to the X end of the current sensor 5, and the (other end) D end of the current sensor 5 is connected to the D phase of the five-phase motor 8. The emitter of the ninth power switch device S9 and the collector of the tenth power switch device S10 are merged and connected to the Y end of the current sensor 5, and the (other end) E end of the current sensor 5 is connected to the E phase of the five-phase motor 8. One end of the No. 1 capacitor C1 is connected to the positive pole of the DC power supply Udc, and one end of the No. 2 capacitor C2 is connected to the negative pole of the DC power supply Udc. The other ends of the No. 1 capacitor C1 and the No. 2 capacitor C2 are connected.

[0067] The neutral point three-level modulated circuit 2 includes a power switch device No. 11 S11, a power switch device No. 12 S12, a power switch device No. 13 S13, a power switch device No. 14 S14, a single-phase conduction element No. 1 D1 and a single-phase conduction element No. 2 D2. The collector of the power switch device No. 11 S11 is connected to the positive electrode of the DC power supply Udc, the emitter of the power switch device No. 11 S11 is connected to the collector of the power switch device No. 12 S12, the emitter of the power switch device No. 12 S12 is connected to the collector of the power switch device No. 13 S13, the emitter of the power switch device No. 13 S13 is connected to the collector of the power switch device No. 14 S14, and the emitter of the power switch device No. 14 S14 is connected to the negative electrode of the DC power supply Udc. The emitter of the twelfth power switch device S12 and the collector of the thirteenth power switch device S13 are both connected to the neutral point N of the five-phase motor 8, the emitter of the eleventh power switch device S11 and the collector of the twelfth power switch device S12 are both connected to the cathode of the first single-phase conduction element D1, the emitter of the thirteenth power switch device S13 and the collector of the fourteenth power switch device S14 are both connected to the anode of the second single-phase conduction element D2, the anode of the first single-phase conduction element D1 is connected to the cathode of the second single-phase conduction element D2, and the anode of the first single-phase conduction element D1 and the cathode of the second single-phase conduction element D2 are both connected to the midpoint of the first capacitor C1 and the second capacitor C2 (that is, the end where the first capacitor C1 and the second capacitor C2 are connected).

[0068] The power switch device No. 1 S1, the power switch device No. 2 S2, the power switch device No. 3 S3, the power switch device No. 4 S4, the power switch device No. 5 S5, the power switch device No. 6 S6, the power switch device No. 7 S7, the power switch device No. 8 S8, the power switch device No. 9 S9, and the power switch device No. 10 S10 are all composed of IGBTs and an anti-parallel freewheeling diode D3, and the operating frequency is set to 10kHz; the power switch devices S1-S10 are low-frequency power switch devices.

[0069] The power switching devices of the upper and lower bridge arms of the five-phase inverter circuit cannot be turned on at the same time. For example, the power switching device No. 1 S1 and the power switching device No. 2 S2 cannot be turned on at the same time. When the power switching device No. 1 S1 is turned on and the power switching device No. 2 S2 is turned off, the potential of the U end between the power switching device No. 1 S1 and the power switching device No. 2 S2 is Udc. When the power switching device No. 1 S1 is turned off and the power switching device No. 2 S2 is turned on, the potential of the U end between the power switching device No. 1 S1 and the power switching device No. 2 S2 is 0.

[0070] Power switching devices S11, S12, S13, and S14 utilize high-performance SiC and are capable of high-frequency operation. Parameter h1 is set to 5-8, meaning the operating frequency is set to 50kHz-80kHz. This achieves a high-frequency neutral point voltage, and thus a high-frequency phase voltage vector. Given parameter h1, the switching frequency of power switching devices S11-S14 in neutral point three-level modulated circuit 2 is h1 times the switching frequency of power switching devices S1-S10 in five-phase inverter circuit 1. The switching frequency of power switching devices S1-S10 is set to 1 / T. s , T s is the control period, the switching frequency of the power switching devices S11-S14 is h1 / T s , thus, the modulation voltage frequency applied to the five-phase motor 8 is h1 / T s , which can reduce the current and torque ripple of the five-phase motor 8. When the eleventh power switch S11, the twelfth power switch S12, the thirteenth power switch S13, and the fourteenth power switch S14 are all in the off state, the five-phase inverter circuit 1 can output the effective vector and the zero vector.

[0071] The neutral point three-level modulator circuit 2 can achieve three different neutral point potentials: Udc, 0, and Udc / 2. When power switches S11 and S12 are on, and S13 and S14 are off, the neutral point potential is Udc. When power switches S11 and S12 are off, and S13 and S14 are on, the neutral point potential is 0. When power switches S11 and S14 are off, and S12 and S13 are on, the neutral point potential is Udc / 2. This neutral point three-level modulator circuit 2 outputs high-frequency signals with a variable duty cycle.

[0072] The signal output end of the main control circuit 3 is connected to the control signal input end of the five-phase inverter circuit 1 and the control signal input end of the neutral point three-level modulator circuit 2 through an isolation circuit.

[0073] The signal input end of the main control circuit 3 is connected to the angle sensor 4 of the five-phase motor 8 , and the current sensors 5 of each phase of the five-phase inverter circuit 1 are connected to the signal input end of the main control circuit 3 .

[0074] The main control circuit 3 has a total of 14 PWM outputs, four of which are output to power switches S11, S12, S13, and S14 in the neutral point three-level modulator circuit 2, and ten are output to power switches S1, S2, S3, S4, S5, S6, S7, S8, S9, and S10 in the five-phase inverter circuit 1. Specifically, the gates of the 14 power switches are connected to the signal output terminals of the main control circuit 3.

[0075] Reference Figure 4 This embodiment also discloses a five-phase motor control method, including the following process:

[0076] Collect sensor signals: The current sensor 5 collects the A-phase current signal CURRENT A, the B-phase current signal CURRENT B, the C-phase current signal CURRENT C, the D-phase current signal CURRENT D, the E-phase current signal CURRENT E, and the rotor position signal θ, and calculates the actual speed ω based on the differential of the rotor position signal r ;

[0077] Set target speed

[0078] Determine whether a fault occurs by the working state of the five-phase motor 8. If a fault occurs, calculate the maximum speed when the fault occurs. If no fault occurs, calculate the maximum speed when the motor is normal.

[0079] Compare the current maximum speed and target speed. If the target speed exceeds the maximum speed, set the target speed to the maximum speed and adjust the target current according to the error between the actual speed and the target speed. If the target speed does not exceed the maximum speed, adjust the target current according to the error between the actual speed and the target speed.

[0080] Design a PI controller as a speed controller to obtain the q-axis (quadrature axis) target current value Set the d-axis (direct axis) target current value is 0;

[0081] Design model predictive current control methods;

[0082] Reference Figure 5 , the model prediction current control method includes:

[0083] Through coordinate transformation, the five-phase current is transformed into the direct-orthogonal coordinate system, including the actual value of the d-axis current i dand the actual value of the q-axis current i q ;

[0084] Determine whether a fault occurs according to the working state of the five-phase motor 8, establish a virtual voltage vector for normal operation and a virtual voltage vector for fault operation, and construct a control set for model prediction current control;

[0085] Normal virtual voltage vector construction method: In the stationary coordinate system, according to the working state of the power switch devices S11-S14, the neutral point potential can be Udc, Udc / 2, 0; according to the working state of the power switch devices S1-S10, the potentials of the U, V, W, X, and Y terminals can be Udc and 0. When the neutral point potentials are Udc, Udc / 2, and 0, 2 can be constructed according to different combinations of the potentials of the U, V, W, X, and Y terminals. 5 = 32 basic voltage vectors, and the voltage vector distribution and amplitude in the fundamental space and harmonic space are different. For example, a large-amplitude basic voltage vector in the fundamental space corresponds to a small-amplitude basic voltage vector in the harmonic space. According to the constraint that the third harmonic voltage vector is 0, two sets of virtual voltage vectors with different amplitudes are combined into V vi , large virtual voltage vector V vb The small virtual voltage vector V is synthesized by the large basic voltage vector and the medium basic voltage vector. vs Composed of a medium base voltage vector and a small base voltage vector;

[0086] A method for constructing a virtual voltage vector during a fault: when a circuit breaker fault occurs in phase z, z=1,2, the duty cycle is set to r, and the duty cycle of the neutral point voltage is fixed. The working modes of the neutral point three-level modulated circuit 2 are divided into two types. One working mode is that within a control cycle, the twelfth power switch device S12 is in the on state, the fourteenth power switch device S14 is in the off state, the states of the eleventh power switch device S11 and the thirteenth power switch device S13 are variable and opposite. When the eleventh power switch device S11 is in the on state and the thirteenth power switch device S13 is in the off state, the neutral point potential is Udc. When the eleventh power switch device S11 is in the off state and the thirteenth power switch device S13 is in the off state, the neutral point potential is Udc. When the device S13 is in the on state, the neutral point potential is Udc / 2; the other working mode is that within one control cycle, the eleventh power switch device S11 is in the off state, the thirteenth power switch device S13 is in the on state, the states of the twelfth power switch device S12 and the fourteenth power switch device S14 are variable and opposite in state. When the twelfth power switch device S12 is in the on state and the fourteenth power switch device S14 is in the off state, the neutral point potential is Udc / 2, and when the twelfth power switch device S12 is in the off state and the fourteenth power switch device S14 is in the on state, the neutral point potential is 0; in the two working modes, 2 can be constructed according to different combinations of the effective phase terminal potentials. (5-z) A basic voltage vector is generated, and a virtual voltage vector is constructed based on the principle of ensuring the amplitude of the fundamental space vector as much as possible while suppressing the harmonic voltage.

[0087] A discrete current prediction model for the five-phase motor 8 is established as follows:

[0088]

[0089] Among them, k is the current calculation cycle, i d (k) is the d-axis current value of k period, i q (k) is the q-axis current value of k period, i d (k+1) is the d-axis predicted current value of the k+1 period, i q (k+1) is the predicted q-axis current value of the k+1 period, u d (k) is the d-axis voltage value of k cycles, u q (k) is the q-axis voltage value of k cycles, T s is the control period, R s is the motor winding resistance, L d is the motor d-axis inductance, L q is the motor q-axis inductance, ψ m is the permanent magnet flux of the motor; ω r is the current actual speed.

[0090] A two-step prediction is used to compensate for the time delay in the processor executing the algorithm. Duty cycle optimization can optimize the voltage vector amplitude. The predicted current model considering duty cycle optimization is established as follows:

[0091]

[0092] in,

[0093] i d (k+2) is the d-axis predicted current value of the k+2 period, i q (k+2) is the predicted q-axis current value of the k+2 period, r i is the duty cycle of the i-th vector in the control set, u di is the d-axis voltage value corresponding to the i-th vector in the control set, u qi is the q-axis voltage value corresponding to the i-th vector in the control set.

[0094] Construct a cost function g based on the d-axis and q-axis current errors i ;

[0095]

[0096] Among them, i d (k+2) is the d-axis predicted current value of the k+2 period, i q (k+2) is the predicted q-axis current value of the k+2 period, and λ is the weight coefficient; is the q-axis target current value, is the d-axis target current value.

[0097] The optimal voltage vector and its duty cycle are obtained by optimizing the cost function;

[0098]

[0099] Among them, v vi is the voltage vector in the control set, v vp is the calculated optimal voltage vector, Represents the ergodic voltage vector v vi Calculate g i , and calculate so that g i smallest vector; Indicates g i to r i The partial derivative of We can find g i The extreme value of g i Optimal duty cycle for minimum value.

[0100] Adaptively adjust the optimal voltage and duty cycle, and use the amplitude ratio of the small virtual voltage vector to the large virtual voltage vector as the threshold w;

[0101]

[0102] Among them, V vs is a small virtual voltage vector, V vb is the large virtual voltage vector;

[0103] When the duty cycle of the optimal voltage vector is less than the threshold, the optimal voltage vector is replaced by a small virtual voltage vector in the same direction, and a new duty cycle is calculated;

[0104] r i '=1.618*r i

[0105] Finally, zero-sequence current control is performed, a zero-sequence current prediction model is established, and zero-sequence current control is performed based on the deadbeat method. The zero-sequence current control is set to 0, and the target zero-sequence voltage is calculated.

[0106]

[0107] in, is the target zero-sequence voltage, is the target zero-sequence current value, set to 0, L s is the inductance of the zero-sequence circuit, i0(k+1) is the predicted zero-sequence current value in the k+1 cycle, R s is the motor winding resistance, T s is the control cycle;

[0108] The selected optimal voltage vector can be synthesized by the basic voltage vectors obtained from different neutral point potentials. However, the vectors mapped in the fundamental wave space and harmonic wave space for different neutral point potentials are the same, but the mapping in the zero-sequence voltage direction is different. According to the target zero-sequence voltage, the proportion of the action time of different neutral point potentials, that is, the duty cycle of the neutral point three-level modulator circuit 2, can be designed and calculated.

[0109] Based on the action time of different neutral point potentials, the states and action time of the power switches S11-S14 are calculated. On this basis, the action time of the basic voltage vector is calculated based on the optimal voltage vector, thereby calculating the states and action time of the power switches S1-S10. Finally, the main control circuit 3 outputs PWM to control the power switches S1-S14.

[0110] If the motor is shut down, the output channel is closed. If the motor is not shut down and continues to run, the sensor signal is collected again and enters the loop.

[0111] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A control method for a five-phase motor, used in a controller of a five-phase motor, characterized by: The controller of the five-phase motor comprises a power circuit, a control circuit and an isolation circuit. The power circuit comprises a five-phase inverter circuit (1) and a neutral point three-level modulator circuit (2). The control circuit comprises a main control circuit (3), an angle sensor (4) and a current sensor (5). The signal output end of the main control circuit (3) is connected to the control signal input end of the five-phase inverter circuit (1) and the control signal input end of the neutral point three-level modulator circuit (2) through the isolation circuit. The signal input end of the main control circuit (3) is connected to the angle sensor (4) of the five-phase motor (8). The current sensors (5) of each phase of the five-phase inverter circuit (1) are connected to the signal input end of the main control circuit (3). The neutral point N of the five-phase motor (8) is connected to the neutral point three-level modulator circuit (2). The control method of the five-phase motor includes the following processes: Collect sensor signals: Current sensor (5) collects A-phase current signal CURRENT A, B-phase current signal CURRENT B, C-phase current signal CURRENT C, D-phase current signal CURRENT D, E-phase current signal CURRENT E, and rotor position signal θ, and calculates actual speed ω based on the differential of the rotor position signal r ; Set target speed Determining whether a fault occurs based on the working state of the five-phase motor (8), and if a fault occurs, calculating the maximum speed at the time of the fault; and if no fault occurs, calculating the maximum speed at the time of normal operation; Compare the current maximum speed with the target speed. If the target speed exceeds the maximum speed, set the target speed to the maximum speed and adjust the target current according to the error between the actual speed and the target speed. If the target speed does not exceed the maximum speed, adjust the target current according to the error between the actual speed and the target speed; Design a PI controller as a speed controller to obtain the q-axis target current value Set the d-axis target current value is 0; Design a model-predictive current control method to calculate the duty cycle of the neutral point three-level modulated circuit (2); The action time of the basic voltage vector is calculated according to the optimal voltage vector, thereby calculating the state and action time of the power switch devices S1-S10, and finally the main control circuit (3) outputs PWM to control the power switch devices S1-S14; If the motor is shut down, the output channel is closed. If the motor is not shut down and continues to run, the sensor signal is collected again and enters the cycle. Model predictive current control methods include: Through coordinate transformation, the five-phase current is transformed into the direct-orthogonal coordinate system, including the actual value of the d-axis current i d and the actual value of the q-axis current i q ; Determine whether a fault occurs according to the working state of the five-phase motor (8), establish a virtual voltage vector in normal state and a virtual voltage vector in fault state, and construct a control set for model prediction current control; The discrete current prediction model of the five-phase motor (8) is established as follows: Among them, k is the current calculation cycle, i d (k) is the d-axis current value of k period, i q (k) is the q-axis current value of k period, i d (k+1) is the d-axis predicted current value of the k+1 period, i q (k+1) is the predicted q-axis current value of the k+1 period, u d (k) is the d-axis voltage value of k cycles, u q (k) is the q-axis voltage value of k cycles, T s is the control period, R s is the motor winding resistance, L d is the motor d-axis inductance, L q is the motor q-axis inductance, ψ m is the permanent magnet flux of the motor, ω r is the current actual speed; The predicted current model considering duty cycle optimization is established as follows: in, i d (k+2) is the d-axis predicted current value of the k+2 period, i q (k+2) is the predicted q-axis current value of the k+2 period, r i is the duty cycle of the i-th vector in the control set, u di is the d-axis voltage value corresponding to the i-th vector in the control set, u qi is the q-axis voltage value corresponding to the i-th vector in the control set; Construct a cost function g based on the d-axis and q-axis current errors i ; Among them, i d (k+2) is the d-axis predicted current value of the k+2 period, i q (k+2) is the predicted q-axis current value of the k+2 period, and λ is the weight coefficient; is the q-axis target current value, is the d-axis target current value; The optimal voltage vector and its duty cycle are obtained by optimizing the cost function; Among them, v vi is the voltage vector in the control set, v vp is the calculated optimal voltage vector, Represents the ergodic voltage vector v vi Calculate g i , and calculate so that g i smallest vector; Indicates g i to r i The partial derivative of Adaptively adjust the optimal voltage and duty cycle, and use the amplitude ratio of the small virtual voltage vector to the large virtual voltage vector as the threshold w; Among them, V vs is a small virtual voltage vector, V vb is the large virtual voltage vector; When the duty cycle of the optimal voltage vector is less than the threshold, the optimal voltage vector is replaced by a small virtual voltage vector in the same direction, and a new duty cycle is calculated; r i '＝1.618*r i Finally, zero-sequence current control is performed, a zero-sequence current prediction model is established, and zero-sequence current control is performed based on the deadbeat method. The zero-sequence current control is set to 0, and the target zero-sequence voltage is calculated. in, is the target zero-sequence voltage, is the target zero-sequence current value, set to 0, L s is the inductance of the zero-sequence circuit, i0(k+1) is the predicted zero-sequence current value in the k+1 cycle, R s is the motor winding resistance, T s is the control cycle; The selected optimal voltage vector can be synthesized from the basic voltage vectors obtained from different neutral point potentials. According to the target zero-sequence voltage, the proportion of the action time of different neutral point potentials can be designed and calculated.

2. A five-phase motor control method as claimed in claim 1, characterized in that: The isolation circuit includes an isolation circuit 1 (6) and an isolation circuit 2 (7), and the isolation circuit 1 (6) and the isolation circuit 2 (7) are circuits with the same structure.

3. The five-phase motor control method according to claim 1, wherein: The angle sensor (4) adopts a rotary transformer.

4. A five-phase motor control method as claimed in claim 1, characterized in that: The five-phase inverter circuit (1) comprises a DC power supply Udc, a No. 1 capacitor C1, a No. 2 capacitor C2, a No. 1 power switch device S1, a No. 2 power switch device S2, a No. 3 power switch device S3, a No. 4 power switch device S4, a No. 5 power switch device S5, a No. 6 power switch device S6, a No. 7 power switch device S7, a No. 8 power switch device S8, a No. 9 power switch device S9 and a No. 10 power switch device S10, wherein the No. 1 power switch device S1, the No. 3 power switch device S3, the No. 5 power switch device S5, The collectors of the seventh power switch device S7 and the ninth power switch device S9 are connected to the positive electrode of the DC power supply Udc, the emitters of the second power switch device S2, the fourth power switch device S4, the sixth power switch device S6, the eighth power switch device S8, and the tenth power switch device S10 are connected to the negative electrode of the DC power supply Udc, the emitter of the first power switch device S1 and the collector of the second power switch device S2 are combined and connected to the U end of the current sensor (5), and the A end of the current sensor (5) is connected to the five-phase motor ( 8), the emitter of the third power switch device S3 and the collector of the fourth power switch device S4 are combined and connected to the V end of the current sensor (5), the B end of the current sensor (5) is connected to the B phase of the five-phase motor (8), the emitter of the fifth power switch device S5 and the collector of the sixth power switch device S6 are combined and connected to the W end of the current sensor (5), the C end of the current sensor (5) is connected to the C phase of the five-phase motor (8), the emitter of the seventh power switch device S7 and the collector of the eighth power switch device S8 ... W end of the current sensor (5), the C end of the current sensor (5) is connected to the C phase of the five-phase motor (8), the emitter of the seventh power switch device S7 and the collector of the eighth power switch device S8 are combined and connected to the W end of the current sensor (5), the C end of the current sensor (5) is connected to the C phase of the five-phase motor (8), the emitter of the seventh power switch device S7 and After the poles are merged, they are connected to the X end of the current sensor (5), the D end of the current sensor (5) is connected to the D phase of the five-phase motor (8), the emitter of the ninth power switch device S9 and the collector of the tenth power switch device S10 are merged and connected to the Y end of the current sensor (5), the E end of the current sensor (5) is connected to the E phase of the five-phase motor (8), one end of the first capacitor C1 is connected to the positive pole of the DC power supply Udc, one end of the second capacitor C2 is connected to the negative pole of the DC power supply Udc, and the other ends of the first capacitor C1 and the second capacitor C2 are connected.

5. A five-phase motor control method as claimed in claim 4, characterized in that: The neutral point three-level modulated circuit (2) comprises an eleventh power switch device S11, a twelfth power switch device S12, a thirteenth power switch device S13, a fourteenth power switch device S14, a first single-phase conduction element D1 and a second single-phase conduction element D2, wherein the collector of the eleventh power switch device S11 is connected to the positive electrode of the DC power supply Udc, the emitter of the eleventh power switch device S11 is connected to the collector of the twelfth power switch device S12, the emitter of the twelfth power switch device S12 is connected to the collector of the thirteenth power switch device S13, the emitter of the thirteenth power switch device S13 is connected to the collector of the fourteenth power switch device S14, and the emitter of the fourteenth power switch device S14 is connected to the collector of the eleventh power switch device S11. The electrode is connected to the negative electrode of the DC power supply Udc, the emitter of the twelfth power switch device S12 and the collector of the thirteenth power switch device S13 are both connected to the neutral point N of the five-phase motor (8), the emitter of the eleventh power switch device S11 and the collector of the twelfth power switch device S12 are both connected to the cathode of the first single-phase conduction element D1, the emitter of the thirteenth power switch device S13 and the collector of the fourteenth power switch device S14 are both connected to the anode of the second single-phase conduction element D2, the anode of the first single-phase conduction element D1 is connected to the cathode of the second single-phase conduction element D2, and the anode of the first single-phase conduction element D1 and the cathode of the second single-phase conduction element D2 are both connected to the midpoint of the first capacitor C1 and the second capacitor C2.

6. A five-phase motor control method as claimed in claim 5, characterized in that: The power switch device No. 1 S1, the power switch device No. 2 S2, the power switch device No. 3 S3, the power switch device No. 4 S4, the power switch device No. 5 S5, the power switch device No. 6 S6, the power switch device No. 7 S7, the power switch device No. 8 S8, the power switch device No. 9 S9, and the power switch device No. 10 S10 are all composed of IGBT and an anti-parallel freewheeling diode D3, and the operating frequency is set to 10kHz; the power switch device No. 11 S11, the power switch device No. 12 S12, the power switch device No. 13 S13, and the power switch device No. 14 S14 use SiC and can operate at high frequency, and the operating frequency is set to 80kHz.

7. A five-phase motor control method as claimed in claim 1, characterized in that: Normal virtual voltage vector construction method: In the stationary coordinate system, according to the working state of the power switch devices S11-S14, the neutral point potential can be Udc, Udc / 2, 0; according to the working state of the power switch devices S1-S10, the potentials of the U, V, W, X, and Y terminals can be Udc and 0. When the neutral point potentials are Udc, Udc / 2, and 0, 2 can be constructed according to different combinations of the potentials of the U, V, W, X, and Y terminals. 5 = 32 basic voltage vectors, and the voltage vector distribution and amplitude in the fundamental space and harmonic space are different. According to the constraint condition that the third harmonic voltage vector is 0, two groups of virtual voltage vectors with different amplitudes are combined into V vi , large virtual voltage vector V vb The small virtual voltage vector V is synthesized by the large basic voltage vector and the medium basic voltage vector. vs It is synthesized by the medium basic voltage vector and the small basic voltage vector.

8. A five-phase motor control method as claimed in claim 1, characterized in that: A method for constructing a virtual voltage vector during a fault: when a z-phase short-circuit fault occurs, z=1,2, the duty cycle is set to r, the duty cycle of the neutral point voltage is fixed, and the working mode of the neutral point three-level modulated circuit (2) is divided into two types. One working mode is that within a control cycle, the twelfth power switch device S12 is in the on state, the fourteenth power switch device S14 is in the off state, the states of the eleventh power switch device S11 and the thirteenth power switch device S13 are variable and opposite in state, when the eleventh power switch device S11 is in the on state and the thirteenth power switch device S13 is in the off state, the neutral point potential is Udc, when the eleventh power switch device S11 is in the off state and the thirteenth power switch device S13 is in the off state, the neutral point potential is Udc. When the switch device S13 is in the on state, the neutral point potential is Udc / 2; the other working mode is that within one control cycle, the eleventh power switch device S11 is in the off state, the thirteenth power switch device S13 is in the on state, the states of the twelfth power switch device S12 and the fourteenth power switch device S14 are variable and opposite in state. When the twelfth power switch device S12 is in the on state and the fourteenth power switch device S14 is in the off state, the neutral point potential is Udc / 2, when the twelfth power switch device S12 is in the off state and the fourteenth power switch device S14 is in the on state, the neutral point potential is 0; in the two working modes, 2 can be constructed according to different combinations of the effective phase terminal potentials. (5-z) A basic voltage vector is generated, and a virtual voltage vector is constructed based on the principle of ensuring the amplitude of the fundamental space vector as much as possible while suppressing the harmonic voltage.

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