Integrated system and control method for current source drive and charging of dual salient pole motor

Abstract

The present invention discloses a current source type driving and charging integrated system and control method for a double-salient-pole motor, comprising a battery, a bidirectional charging and discharging converter, a current source type converter, an electrically excited double-salient-pole motor, and a switching switch, wherein the two-section split excitation winding of the double-salient-pole motor is reused as the DC side energy storage inductor of the current source type converter. In the driving operation mode, the two sections of the excitation winding are connected in parallel in the same direction. By controlling the charge and discharge converter, a constant current can be provided to the DC side when the motor speed is low, and energy feedback can be achieved during the four-quadrant operation and braking of the motor. In the charging operation mode, the two sections of the excitation winding are connected in reverse series to achieve a demagnetization effect, thereby charging the battery while achieving zero torque output. The system is suitable for the driving and charging integrated system of electric vehicles, has the advantages of fewer switching devices and high reliability, saves space and cost, and reduces system losses.

Description

Technical Field

[0001] This invention relates to a topology and control method for an integrated current source drive and charging system for a doubly salient pole motor with a multiplexed excitation winding for electric vehicles, belonging to the field of motor systems and control. Background Art

[0002] Currently, the mainstream drive motors used in electric vehicles are permanent magnet motors such as brushless DC motors and permanent magnet synchronous motors, as well as non-permanent magnet motors such as induction motors and switched reluctance motors. Brushless DC motors are low-cost and simple in structure and control, but their square wave current control method results in significant torque ripple compared to permanent magnet synchronous motors. Permanent magnet synchronous motors have high power density and low torque ripple, maintaining high efficiency at all speeds, making them particularly suitable for the frequent start-stop and acceleration / deceleration applications of electric vehicles, thus becoming the preferred solution for most manufacturers. However, due to the presence of permanent magnets, magnet degradation can occur during high-speed operation with weakened magnets and high-temperature vibration. Furthermore, the high price of permanent magnet materials makes it difficult to reduce the cost of the motor system, preventing permanent magnet motors from completely dominating the electric vehicle market. Induction motors, as the most widely used non-permanent magnet motors, are simple in structure, low in cost, and can operate stably under harsh conditions. With mature vector control technology, they offer excellent speed regulation performance and have been applied in many commercial electric vehicles. Their main disadvantages are lower efficiency at low speeds and higher losses due to induced current in the rotor windings. Switched reluctance motors have a simple and reliable structure and the lowest cost. At the same time, their wide speed range and strong heat dissipation capabilities enable them to adapt to various complex operating conditions of commercial electric vehicles. However, switched reluctance motors can only output power in the inductance rising region, resulting in low core utilization. Furthermore, their inherent torque ripple and noise also limit the promotion of switched reluctance motors in the field of household electric vehicles.

[0003] Besides the traditional motor types mentioned above, the doubly salient pole motor, as a new type of motor, is also suitable for applications in the electric vehicle field. The doubly salient pole motor is very similar to the switched reluctance motor in its stator and rotor structure, both being salient pole structures with no windings on the rotor side. Based on the excitation source on the stator side, it is divided into permanent magnet doubly salient pole motors and electrically excited doubly salient pole motors. Doubly salient pole motors can output power in both the rising and falling inductance regions, improving core utilization and power density. Electrically excited doubly salient pole motors use low-cost DC windings for excitation on the stator side. Controllable excitation makes magnet adjustment and speed control simple and convenient, reducing the requirements for the controller. Compared to permanent magnet doubly salient pole motors, the absence of permanent magnets reduces costs by about 40%. Although the added excitation windings inevitably increase losses, this loss is very limited in the operating conditions of high-power commercial electric vehicles, forklifts, and other applications. Therefore, the low-cost, high-reliability, and excellent speed-regulating performance of the electrically excited doubly salient pole motor has great potential in the field of electric vehicle drive motor applications.

[0004] Currently, the mainstream power converters in integrated drive / charging systems both domestically and internationally are two-stage cascaded converters consisting of a DC / DC converter and a DC / AC converter. The coupling relationship between the preceding and following stages, as well as the stability requirements of system operation, significantly limit the application of cascaded converters. Furthermore, the multi-stage structure requires additional power devices, increasing costs and complicating control methods, hindering their widespread adoption. Technological advancements have driven the rise of current-source converters. Current-source converters, with their boost characteristics as inverters and buck characteristics as rectifiers, are gaining increasing traction in medium- and high-power applications, such as grid-connected photovoltaics and shipbuilding. The boost voltage requirements from the battery side to the motor side during electric vehicle driving and the buck voltage requirements from the grid side to the battery side during charging perfectly match the characteristics of current-source converters, making them highly adaptable for integrated drive / charging systems. Summary of the Invention

[0005] To address the aforementioned issues, this invention proposes a topology and control method for a dual salient pole motor current source type drive and charging integrated system with reused excitation windings, which enables integrated control of electric vehicle drive and charging.

[0006] A dual salient pole motor current source type drive and charging integrated system includes a battery, a charge-discharge bidirectional converter, a current source converter, an electrically excited dual salient pole motor, an AC filter capacitor, switching switches K1, K2, and K3, and a detection and control circuit. The battery is connected to the input terminal of the charge-discharge bidirectional converter. The upper input terminal of the current source converter is connected to the midpoint of the bridge arm of the charge-discharge bidirectional converter through switching switch K2 and the excitation winding of the electrically excited dual salient pole motor in sequence. The lower input terminal is directly connected to the midpoint of the bridge arm of the charge-discharge bidirectional converter. The excitation winding is split into two windings F1 and F2, and winding F2 is connected in series with switching switch K1. The midpoint of the bridge arm of the current source converter is connected to the AC power grid through the armature winding of the electrically excited dual salient pole motor and switching switch K3 in sequence, and an AC filter capacitor is connected in parallel between the AC power grid and the AC power grid.

[0007] The integrated current-source drive and charging system for the doubly salient pole motor also includes a sampling signal control system. This system samples the excitation current signal and armature current signal of the doubly salient pole motor using a current sensor and performs various controls, including mode switching. In drive mode, the excitation winding is reused as the DC-side energy storage inductor of the current-source converter through the control of a switching switch. Combined with the drive control strategy, the battery drives the doubly salient pole motor through the current-source converter. In charging mode, the armature winding is reused as the AC-side filter inductor through the control of a switching switch. The AC grid charges the battery through the doubly salient pole motor armature winding, current-source converter, excitation winding, and bidirectional charge / discharge converter, combined with the charging control strategy.

[0008] Preferably, the bidirectional charge-discharge converter includes three series branches, each of which includes diode VD1 and switch S1, switch S2 and diode VD2, and switch S3 and diode VD3 connected in sequence. The three branches are connected in parallel to form three bridge arm branches. The upper input terminal of the current source converter is connected to the excitation winding F2 through a switching switch K2. F2 is connected to the midpoint of the bridge arm between S3 and VD3 through a switching switch K1. The excitation winding F1 is connected to the midpoint of the bridge arm between S2 and VD2. The lower input terminal of the current source converter is connected to the midpoint of the bridge arm between S1 and VD1.

[0009] Preferably, the excitation winding of the electrically excited doubly salient pole motor is reused as the DC-side energy storage inductor of the current source converter. By switching the switching switches K1 and K2 to positions a and b, the series or parallel control of the excitation windings F1 and F2 can be realized. Specifically, in the drive operation mode, both switching switches K1 and K2 are switched to position a, so that the excitation windings F1 and F2 are connected in parallel and then connected to the DC side of the current source converter; in the charging operation mode, both switching switches K1 and K2 are switched to position b, so that the excitation windings F1 and F2 are connected in reverse series and then connected to the DC side of the current source converter.

[0010] This invention also discloses a control method for an integrated current source drive and charging system for a doubly salient pole motor.

[0011] When the dual salient pole motor current source type drive and charging integrated system with reused excitation winding is operating in drive mode, the specific control strategy is as follows:

[0012] Step 1: Control the switching switches K1 and K2 to close at point a. The two excitation windings are connected in parallel, and the two excitation currents together provide DC current for the current source converter. Switch K3 closes naturally, so that the end of the three-phase armature winding of the motor, that is, the end closest to switch K3, is short-circuited, forming a star winding connection.

[0013] Step 2: Sample the two excitation currents respectively. In the bidirectional charge-discharge converter, switch S1 is always on, while S2 and S3 are in PWM state, thereby controlling the current i of the excitation windings F1 and F2. f1 i f2 Each is kept constant, so that i f1 i f2 They are of equal size. The battery output supplies power to the doubly salient pole motor via switching transistors S2 and S3, excitation windings F1 and F2, and a current source converter.

[0014] Step 3: Detect the position signal and armature winding current of the doubly salient pole motor. Based on the collected position signal and armature current signal, control the current source converter to operate in inverter mode. Combine the dual closed-loop control method of speed and current to control the inverter output current and realize the drive operation of the doubly salient pole motor.

[0015] Preferably, the control strategy of the motor drive system needs to be adjusted when the electric vehicle decelerates and brakes. Braking mode is another type of drive mode. In this mode, the motor operates as a generator due to the electric vehicle's deceleration and braking, generating armature current. This current energy is the braking energy, which is recovered through energy feedback. The specific braking control strategy is as follows:

[0016] Step 3.1: Sample the excitation current and armature current using a current sensor. To prevent incorrect entry into braking mode due to ripple, set appropriate upper and lower thresholds, and set the DC-side current i of the current source converter. dc The quadrature axis current i on the AC side of the motor q The hysteresis judgment stage performs a bitwise OR operation on the output signals of the two judgments, and uses the OR gate output signal to determine whether the system is in braking mode. Step 3.2: After determining that the system has entered braking mode, control switch S1 is turned off, braking energy flows through VD1, and the switching on and off of switches S2 and S3 controls the braking of i... f1 i f2 The constant control switches the excitation winding mode according to the magnitude of the excitation current: when the excitation current is small, it switches to the excitation winding charging mode: switching transistors S2 and S3 are turned on, and braking energy charges the excitation windings F1 and F2 through VD1 and S2 and S3, thus enabling i f1 i f2 Increase; when the excitation current is large, it is the excitation winding energy feeding mode: switches S2 and S3 are turned off, and braking energy is fed back to the battery side via VD1, and then flows through VD2 and VD3 through the excitation windings F1 and F2 to form a closed loop. In this mode, the battery acts as the excitation energy absorption source, making the current i in the excitation winding... f1 i f2Reduce. Step 3.3: Based on the sampled values ​​of the motor armature current and rotor position, control the current source inverter to output reverse current according to the braking command to realize the motor braking function.

[0017] Preferably, to reduce the parallel excitation winding current i f1 and i f2 The generated ripple enables the current source converter to obtain a high-quality DC input current. A dual-edge modulation strategy is used to control S2 and S3, specifically: 1) Simultaneously generating rising and falling sawtooth waves of the same frequency, which are respectively used as i f1 and i f2 1) The control signal generates a carrier wave; 2) The rising sawtooth wave carrier wave is compared with the duty cycle d2 of switch S2. If d2 is greater than the rising sawtooth wave carrier wave, S2 is turned on; otherwise, S2 is turned off; 3) The falling sawtooth wave carrier wave is compared with the duty cycle d3 of switch S3. If d3 is greater than the falling sawtooth wave carrier wave, S3 is turned on; otherwise, S3 is turned off. The dual-edge modulation method can be applied not only to normal driving modes but also to braking modes.

[0018] When the dual salient pole motor current source type drive and charging integrated system with reused excitation winding is operating in charging mode, the specific control strategy is as follows:

[0019] 1) When switches K1 and K2 are closed at point b, the two excitation windings are connected in reverse series, corresponding to the excitation current i f1 and i f2 Equal in size but opposite in direction, the demagnetization function of the doubly salient pole motor is realized in charging mode. Switch K3 is turned on, connecting the three-phase armature winding of the doubly salient pole motor to the AC grid. At this time, the three-phase armature winding of the doubly salient pole motor is reused as the filter inductor of the LC filter on the grid side. 2) In the bidirectional charge-discharge converter, the switches S1, S2, and S3 are turned off, and the current source converter operates in rectification mode, transmitting electrical energy to charge the battery through VD1, VD2, and VD3. 3) The three-phase current of the motor is sampled by the current sensor in the subsequent stage, and the phase-locked loop of the AC grid voltage is combined to determine the AC current angle on the grid side. A dual closed-loop control strategy of output DC current and AC current is adopted to make the current source converter operate in rectifier mode and charge the battery according to the charging command.

[0020] Beneficial effects

[0021] Compared to traditional integrated drive / charging systems, the dual salient pole motor current source drive and charging integrated system with reused excitation windings has two significant advantages: Firstly, by reusing the excitation winding as a DC-side energy storage inductor, the additional DC-side inductor required by the current source converter is eliminated, as is the DC power supply required for the excitation of a traditional electrically excited motor. In terms of power loss, this is equivalent to reducing excitation winding losses. Secondly, the boost voltage requirements from the battery side to the motor side during electric vehicle driving and the step-down voltage requirements from the grid side to the battery side during charging perfectly match the boost voltage characteristics of the current source converter when used as an inverter and the step-down voltage characteristics when used as a rectifier. Applying the current source converter to the integrated drive / charging system has very high adaptability. This system does not require an additional DC / DC converter, eliminating the stability risks and additional costs associated with cascaded systems. Although a bidirectional charge / discharge converter needs to be added on the battery side, the required components are few, the control method is simple and reliable, and it has significant practical application value. Attached Figure Description

[0022] Figure 1 A block diagram of the topology of a dual salient pole motor current source type drive and charging integrated system with reused excitation windings;

[0023] Figure 2 The simulation waveform of motor speed in drive mode;

[0024] Figure 3 For the motor armature current i in drive mode a Simulation waveform diagram;

[0025] Figure 4 For the motor excitation current i in drive mode f1 Simulation waveform diagram;

[0026] Figure 5 For the motor excitation current i in drive mode f2 Detailed simulation waveform diagram;

[0027] Figure 6 The simulation waveform of the DC-side input current of the current-source inverter in drive mode;

[0028] Figure 7 The simulation waveform of motor speed in braking mode;

[0029] Figure 8 The simulation waveform of motor torque in braking mode;

[0030] Figure 9 For the motor armature current i in braking mode a Simulation waveform diagram;

[0031] Figure 10 For the motor excitation current i in braking mode f1Detailed simulation waveform diagram;

[0032] Figure 11 The simulation waveform of the battery-side current is shown below.

[0033] Figure 12 Detailed waveform of simulated energy feedback current on the battery side;

[0034] Figure 13 Simulated waveform of battery charging current in charging mode;

[0035] Figure 14 For the excitation current i in charging mode f1 Simulation waveform diagram. DETAILED DESCRIPTION

[0036] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0037] This invention discloses an integrated current-source drive and charging system and control method for a doubly salient pole motor, comprising a battery, a bidirectional charge-discharge converter, a current-source converter, an electrically excited doubly salient pole motor, an AC filter capacitor, and a switching switch. The two split excitation windings of the doubly salient pole motor are reused as the DC-side energy storage inductor of the current-source converter. In drive mode, the ends of the armature windings of the doubly salient pole motor are completely short-circuited by the switch, and the two excitation windings are connected in parallel in the same direction. The battery drives the doubly salient pole motor through the bidirectional charge-discharge converter and the current-source converter. By controlling the bidirectional charge-discharge converter, a constant current is provided to the DC side when the motor speed is low, realizing four-quadrant operation of the electrically excited doubly salient pole motor and energy feedback during braking. In charging mode, the AC grid is connected to the armature windings of the doubly salient pole motor by the switch, and the battery is charged through the power converter and the bidirectional charge-discharge converter. The two excitation windings of the doubly salient pole motor are connected in series to achieve a demagnetizing effect, eliminating the torque generated during charging. This system is suitable for the integrated drive and charging system of electric vehicles. It has the advantages of fewer switching devices, simple structure, and high reliability. It can also save space and cost for electric vehicles and reduce system losses.

[0038] Example 1:

[0039] This invention proposes a topology for an integrated current source drive and charging system for a doubly salient pole motor with a reused excitation winding, as follows: Figure 1As shown, the system includes a battery, a bidirectional charge-discharge converter, a current source converter, an electrically excited doubly salient pole motor, an AC filter capacitor, switching switches K1, K2, and K3, and a detection and control circuit. The battery is connected to the input terminal of the bidirectional charge-discharge converter. The upper input terminal of the current source converter is connected to the midpoint of the bridge arm of the bidirectional charge-discharge converter via switching switch K2 and the excitation winding of the electrically excited doubly salient pole motor. The lower input terminal is directly connected to the midpoint of the bridge arm of the bidirectional charge-discharge converter. The excitation winding is split into two windings, F1 and F2, with winding F2 connected in series with switching switch K1. The midpoint of the bridge arm of the current source converter is connected to the AC power grid via the armature winding of the electrically excited doubly salient pole motor and switching switch K3. An AC filter capacitor is connected in parallel between the AC power grid and the current source converter. By controlling K3, the other end of the armature winding can be connected to the AC power grid or completely short-circuited to form a star winding connection.

[0040] The bidirectional charge-discharge converter includes three series branches. Each series branch includes diode VD1 and switch S1, switch S2 and diode VD2, and switch S3 and diode VD3 connected in sequence. The three branches are connected in parallel to form three bridge arm branches. Specifically, the upper input terminal of the current source converter is connected to the excitation winding F2 via switch K2. F2 is connected to the midpoint of the bridge arm between S3 and VD3 via switch K1. The excitation winding F1 is connected to the midpoint of the bridge arm between S2 and VD2. The lower input terminal of the current source converter is connected to the midpoint of the bridge arm between S1 and VD1.

[0041] The excitation winding of the electrically excited doubly salient pole motor is split into two windings, F1 and F2. One end of F1 and F2 is connected to the bridge arm formed by the switching transistors S2 and S3 and the diodes VD2 and VD3 in the bidirectional charge-discharge converter, respectively. The other end is connected to the switching switches K1 and K2, which reuse the excitation winding of the electrically excited doubly salient pole motor as the DC-side energy storage inductor of the current source converter. By controlling K1 and K2, the two split excitation windings can be connected in parallel in the same direction or in series in opposite directions. While providing the excitation magnetic field to the motor, windings F1 and F2 also play an energy storage role in the converter as DC-side inductors. The excitation windings at both point a and point b via K1 and K2 have multiplexing functions.

[0042] The current source converter includes switching transistors S4, S5, S6, S7, S8, and S9, and diodes VD4, VD5, VD6, VD7, VD8, and VD9 connected in series with them. Specifically, S4, VD4, S5, and VD5 are connected in series in sequence, S6, VD6, S7, and VD7 are connected in series in sequence, and S8, VD8, S9, and VD9 are connected in series in sequence, forming three series branches. These three series branches are connected in parallel to form the three bridge arms of the current source converter. The midpoints of the three bridge arms are connected to the AC power grid through armature windings A, B, and C, respectively.

[0043] The controller collects data such as the two-stage excitation current, three-phase armature current, rotor position, and three-phase grid-side voltage of the doubly salient pole motor through various sensors. Based on the collected data and control strategy, it drives the bidirectional charge-discharge converter and the current source converter to enable the motor to operate according to instructions under different operating conditions.

[0044] Example 2:

[0045] This example implements a control strategy for an electric vehicle in drive mode, based on Example 1.

[0046] 1. Control switches K1 and K2 to close at point a, the two excitation windings are connected in parallel, and the two excitation currents together provide DC current to the current source converter. The current source converter is in inverter mode, and switch K3 closes naturally, so that the end of the three-phase armature winding of the motor, that is, the end closest to switch K3, is short-circuited, forming a star winding connection.

[0047] 2. In the bidirectional charge-discharge converter, switch S1 is always on, sampling the two excitation currents respectively. The difference between the reference value and the sampled value is used to obtain the duty cycle of S2 and S3 through a PI regulator, driving S2 and S3 to control the current i in the excitation windings F1 and F2. f1 i f2 Each is kept constant, so that i f1 i f2 They are of equal size. The battery output supplies power to the doubly salient pole motor via switching transistors S2 and S3, excitation windings F1 and F2, and a current source converter.

[0048] 3. Based on the signals obtained from the motor armature winding current sensor and position sensor, the current source converter is controlled in inverter operating mode. Combining the speed and current dual closed-loop control method, the switching transistors in the current source inverter are controlled to turn on and off according to the on / off logic of the traditional control method. The current source inverter outputs current to realize the driving operation of the doubly salient pole motor.

[0049] Example 3:

[0050] This example implements a control strategy for an electric vehicle in braking mode, based on Example 1.

[0051] 1. Sample the excitation current and armature current using a current sensor, set appropriate upper and lower thresholds, and set the DC-side current i of the current source converter. dc The quadrature axis current i on the AC side of the motor q The hysteresis judgment stage performs a bitwise OR operation on the output signals of the two judgments, and the OR gate output signal determines whether the system is in braking mode.

[0052] 2. After confirming that the system has entered braking mode, control switch S1 is turned off, braking energy flows through VD1, and the switching on and off of switches S2 and S3 controls the braking of i. f1 i f2 The constant control is achieved by outputting the control signals S2 and S3 from a PI regulator that controls the excitation current. The switching between the excitation winding charging mode and the excitation winding feeding mode is realized according to the magnitude of the excitation current.

[0053] When the excitation current is low, the system switches to the excitation winding charging mode: Switches S2 and S3 are turned on, and braking energy charges the excitation windings F1 and F2 via VD1 and S2 / S3, causing i f1 i f2 Increase;

[0054] When the excitation current is large, the system switches to the excitation winding energy feeding mode: switches S2 and S3 are turned off, and the braking energy is fed back to the battery side via VD1, and then flows through VD2 and VD3 through the excitation windings F1 and F2 to form a closed loop. In this mode, the battery acts as the excitation energy feeding source, causing the current i in the excitation winding to... f1 i f2 Decrease.

[0055] 3. Based on the sampled values ​​of the motor armature current and rotor position, the current source inverter is controlled to output reverse current according to the braking command to realize the electromagnetic braking function of the motor.

[0056] Example 4:

[0057] Based on Example 1, this example employs a dual-edge modulation strategy to control S2 and S3 to improve the DC input current quality of the current source converter. Specifically:

[0058] 1. Simultaneously generate rising and falling sawtooth waves of the same frequency, which are respectively used as i f1 and i f2 The carrier wave generated by the control signal;

[0059] 2. Compare the rising sawtooth wave carrier with the duty cycle d2 of switch S2. If d2 is greater than the rising sawtooth wave carrier, S2 is turned on; otherwise, S2 is turned off.

[0060] 3. Compare the falling sawtooth wave carrier with the duty cycle d3 of switch S3. If d3 is greater than the falling sawtooth wave carrier, S3 is turned on; otherwise, S3 is turned off.

[0061] Example 5:

[0062] This example implements a control strategy for electric vehicles in charging mode, based on Example 1.

[0063] 1. Switches K1 and K2 are closed at point b, and the two excitation windings are connected in reverse series, corresponding to the excitation current i. f1 and i f2 With equal size and opposite direction, the demagnetization function of the double salient pole motor is realized in the charging mode. When switch K3 is turned on, the three-phase armature winding of the double salient pole motor is connected to the AC power grid. At this time, the three-phase armature winding of the double salient pole motor is reused as the filter inductor of the LC filter on the grid side.

[0064] 2. In the bidirectional charge-discharge converter, the switching transistors S1, S2, and S3 are turned off, and the current source converter operates in rectification mode, transmitting electrical energy to charge the battery through VD1, VD2, and VD3.

[0065] 3. The three-phase current of the motor is sampled by the current sensor in the later stage, and the phase-locked loop of the AC grid voltage is used to determine the AC current angle on the grid side. A dual closed-loop control strategy of output DC current and AC current is adopted to make the current source converter work in rectifier mode and charge the battery according to the charging command.

[0066] Test Example 1:

[0067] Based on the integrated drive and charging system and its drive control strategy for a doubly salient pole motor with a reused excitation winding described in Examples 1, 2, and 4, the drive operation of the integrated system is simulated. The specific simulation conditions are as follows: the battery supply voltage is 100V, the excitation current reference value is set to 10A (i.e., the DC input current of the current source inverter is 20A), the electrically excited doubly salient pole motor is a 12 / 10 pole structure, the armature winding resistance and inductance are 0.1Ω and 5.6mH respectively, the excitation winding resistance and inductance are 0.4Ω and 13mH respectively, the mutual inductance between the excitation winding and the armature winding is a sinusoidal wave with an amplitude of 6.78mH that varies with the rotor electrical angle, and the motor moment of inertia is 0.074 kg·m. 2 The load torque is set to 5 N·m, and the control command is to increase the speed from 0 to 400 rpm and maintain it constant.

[0068] Figure 2 The figure shows the motor speed waveform during simulation. As can be seen from the figure, the motor gradually increases its speed to 400 rpm at 0 seconds and then maintains a constant speed. Figure 3 For the motor armature current i a The waveform diagram shows that the three-phase currents are symmetrical and have good sinusoidal properties. Figure 4 For the excitation current i f1 Waveform diagram Figure 5 For the excitation current i f2 The waveform details show that the two excitation currents are constant, equal in magnitude and in the same direction during the entire drive operation, and the current ripple is less than 0.08A. Figure 6The waveform of the DC-side input current of the current-source inverter is shown. This current is the sum of the two excitation currents, with a constant magnitude of 20A and a ripple of less than 0.14A, providing a high-quality input current for the current-source inverter. Simulation results show that under the above simulation conditions, the motor can achieve normal starting and steady-state operation. The excitation current and DC-side current ripple are small and of high quality, indicating that the dual-salient pole motor current-source drive and charging integrated system with multiplexed excitation windings can achieve normal drive function and has good operating characteristics.

[0069] Test Example 2:

[0070] Based on the integrated current-source drive and charging system and its braking control strategy for a doubly salient pole motor with a reused excitation winding described in Examples 1, 3, and 4, the braking operation of the integrated system is simulated. The specific simulation conditions are as follows: the battery supply voltage is 100V, the excitation current reference value is set to 10A (i.e., the DC input current of the current-source inverter is 20A), the electrically excited doubly salient pole motor is a 12 / 10-pole structure, the armature winding resistance and inductance are 0.1Ω and 5.6mH respectively, the excitation winding resistance and inductance are 0.4Ω and 13mH respectively, the mutual inductance between the excitation winding and the armature winding is a sinusoidal wave with an amplitude of 6.78mH that varies with the rotor electrical angle, and the motor moment of inertia is 0.074 kg·m. 2 The load torque is set to 5 N·m, and the control command is to reduce the speed from 500 rpm to 100 rpm.

[0071] Figure 7 , Figure 8 The simulation waveforms of motor speed and torque show that the motor speed drops from 500 rpm to 100 rpm in 1 second and then remains constant. The torque reverses according to the control command in 1 second, causing the speed to decrease. After 1.22 seconds, the torque gradually increases until the speed stabilizes at 100 rpm without speed overshoot. Figure 9 armature current i a The diagram shows that the three-phase current is symmetrical and has a good sinusoidal degree. At 1 second, the output current reverses to output negative torque, and the motor enters the braking mode. After 1.22 seconds, the positive current gradually recovers, and the motor exits the braking mode. Figure 10 For the excitation current i f1 The waveform details show that the excitation current remains constant throughout the entire drive operation. At 1 second and 1.22 seconds, the excitation current spikes due to the switching between drive mode and braking mode, but the spikes are less than 0.2A, which is within the allowable range. Figure 11 , Figure 12The diagram shows the detailed waveforms of the battery-side current and its energy feedback current. The negative current is the battery charging current. Due to the chopper control of the switching transistor, the feed current is pulsed, and its maximum value is determined by the given value of the excitation current. Simulation results show that under the above simulation conditions, the motor can achieve energy feedback during braking while maintaining a constant excitation current. Although there are spikes during the switching between drive and braking modes, these spikes are small and within acceptable limits, not affecting the normal operation of the system.

[0072] Test Example 3:

[0073] Based on the integrated current source drive and charging system and its charging control strategy for the doubly salient pole motor with reused excitation windings described in Examples 1 and 5, the charging operation of the integrated system is simulated. The specific simulation conditions are as follows: The electrically excited doubly salient pole motor has a 12 / 10 pole structure. The armature winding resistance and inductance are 0.1Ω and 5.6mH, respectively, and the excitation winding resistance and inductance are 0.4Ω and 13mH, respectively. The mutual inductance between the excitation winding and the armature winding is a sinusoidal wave with an amplitude of 6.78mH that varies with the rotor electrical angle. The motor's moment of inertia is 0.074 kg·m. 2 The grid side is a three-phase AC power with a phase voltage of 220V and a frequency of 50Hz. The control command is to achieve constant current charging with a charging current of 6A.

[0074] Figure 13 This is a waveform diagram of the charging current on the battery side, where the charging current is the excitation current i. f2 The current is constant at 6A and the ripple is within 0.1A; Figure 14 For the excitation current i f1 The waveform diagram shows that the two excitation windings are connected in reverse series, therefore i f1 The current is negative, and i f1 Equal in magnitude but opposite in direction, the output torque is eliminated; however, since the simulation results are relatively ideal, the torque output is 0 during charging, so the torque waveform is not shown here. The simulation results show that this system can achieve zero torque output during constant current charging, meeting the charging requirements of integrated systems.

[0075] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A dual-salient pole motor current source type integrated drive and charging system, characterized in that, The system includes a battery, a bidirectional charge-discharge converter, a current source converter, an electrically excited doubly salient pole motor, an AC filter capacitor, switching switches K1, K2, and K3, and a detection and control circuit. The battery is connected to the input terminal of the bidirectional charge-discharge converter. The upper input terminal of the current source converter is connected to the midpoints of the second and third bridge arms of the bidirectional charge-discharge converter via switching switch K2 and the excitation winding of the electrically excited doubly salient pole motor, respectively. The lower input terminal is directly connected to the midpoint of the first bridge arm of the bidirectional charge-discharge converter. The excitation winding is split into two windings, F1 and F2, with winding F2 connected in series with switching switch K1. The midpoints of the bridge arms of the current source converter are connected to the AC power grid via the armature winding of the electrically excited doubly salient pole motor and switching switch K3. An AC filter capacitor is connected in parallel between the midpoint of the bridge arm of the current source converter and the armature winding of the motor. The integrated current-source drive and charging system for the doubly salient pole motor also includes a sampling signal control system. This system samples the excitation current signal and armature current signal of the doubly salient pole motor using a current sensor and performs various controls, including switching between drive and charging modes. In drive mode, the excitation winding is reused as the DC-side energy storage inductor of the current-source converter through a switching switch. Combined with the drive control strategy, the battery drives the doubly salient pole motor through the current-source converter. In charging mode, the armature winding is reused as the AC-side filter inductor through a switching switch. The AC grid charges the battery through the doubly salient pole motor armature winding, current-source converter, excitation winding, and bidirectional charge / discharge converter, combined with the charging control strategy.

2. The integrated drive and charging system for a doubly salient pole motor current source type according to claim 1, characterized in that, The bidirectional charge-discharge converter includes three series branches. Each series branch includes diode VD1 and switch S1, switch S2 and diode VD2, and switch S3 and diode VD3 connected in sequence. The three branches are connected in parallel to form three bridge arm branches. The upper input terminal of the current source converter is connected to the excitation winding F2 through the switching switch K2. F2 is connected to the midpoint of the bridge arm between S3 and VD3 through the switching switch K1. The excitation winding F1 is connected to the midpoint of the bridge arm between S2 and VD2. The lower input terminal of the current source converter is connected to the midpoint of the bridge arm between S1 and VD1.

3. The integrated drive and charging system for a doubly salient pole motor current source type according to claim 2, characterized in that, The excitation winding of the electrically excited doubly salient pole motor is reused as the DC-side energy storage inductor of the current source converter. By switching the switching switches K1 and K2 to positions a and b, the series or parallel control of the excitation windings F1 and F2 can be realized. Specifically, in the drive operation mode, both switching switches K1 and K2 are switched to position a, so that the excitation windings F1 and F2 are connected in parallel and then connected to the DC side of the current source converter; in the charging operation mode, both switching switches K1 and K2 are switched to position b, so that the excitation windings F1 and F2 are connected in reverse series and then connected to the DC side of the current source converter.

4. The control method for the integrated drive and charging system of a doubly salient pole motor current source type according to claim 2 or 3, characterized in that, When the system is running in drive mode, the following steps are included: Step 1: Control the switching switches K1 and K2 to close at point a. The two excitation windings are connected in parallel. The two excitation currents together provide DC current to the current source converter. The current source converter is in inverter mode. Switch K3 closes naturally. The ends of the three-phase armature windings of the motor are short-circuited, forming a star winding connection. Step 2: Sample the currents of the two excitation windings F1 and F2 respectively. In the bidirectional charge-discharge converter, switch S1 is always on, while S2 and S3 are in PWM state, thereby controlling the current i of the excitation windings F1 and F2. f1 i f2 Each is kept constant, so that i f1 =i f2 The battery output supplies power to the dual salient pole motor via switching transistors S2 and S3, excitation windings F1 and F2, and a current source converter. Step 3: Detect the position signal and armature winding current of the doubly salient pole motor. Based on the collected position signal and armature current signal, control the current source converter to operate in inverter mode. Combine the dual closed-loop control method of speed and current to control the inverter output current, thereby realizing the drive mode operation and braking mode operation of the doubly salient pole motor.

5. The control method for the integrated current source drive and charging system of a doubly salient pole motor according to claim 4, characterized in that, To reduce the current i in the parallel excitation winding f1 and i f2 The resulting ripple enables the current source converter to obtain a high-quality DC input current. A dual-edge modulation strategy is used to control S2 and S3, specifically: Step 2.1: Simultaneously generate rising sawtooth waves and falling sawtooth waves of the same frequency, which are respectively used as i f1 and i f2 The carrier wave generated by the control signal; Step 2.2: Compare the rising sawtooth wave carrier with the duty cycle d2 of the switch S2. If d2 is greater than the rising sawtooth wave carrier, S2 is turned on; otherwise, S2 is turned off. Step 2.3: Compare the falling sawtooth wave carrier with the duty cycle d3 of the switch S3. If d3 is greater than the falling sawtooth wave carrier, S3 is turned on; otherwise, S3 is turned off.

6. The control method for the integrated current source drive and charging system of a doubly salient pole motor according to claim 5, characterized in that, The specific steps for implementing the braking mode operation of the dual salient pole motor in step 3 are as follows: Step 3.1: Sample the excitation current and armature current using a current sensor, set upper and lower thresholds, and set the DC-side current i of the current source converter. dc The quadrature axis current i on the AC side of the motor q The hysteresis judgment step inputs the output signal after the two judgments into the logic OR gate. The output signal of the OR gate determines whether the system is in braking mode. If the judgment is yes, proceed to step 3.2; otherwise, continue to run in driving mode. Step 3.2: After determining that the system has entered braking mode, control switch S1 is turned off, braking energy flows through VD1, and the switching on and off of switches S2 and S3 controls the braking of i. f1 i f2 The constant control determines the excitation winding charging mode and excitation winding feeding mode based on the magnitude of the excitation current in order to switch modes. Step 3.3: Based on the motor rotor position and armature current sampling value, control the current source inverter to output reverse current according to the braking command to realize the motor braking function.

7. The control method for the integrated current source drive and charging system of a doubly salient pole motor according to claim 6, characterized in that, The control method for the excitation winding charging mode is as follows: Switches S2 and S3 are turned on, and braking energy charges the excitation windings F1 and F2 via VD1 and S2 / S3, causing i f1 i f2 Increase; The control method for the excitation winding energy feeding mode is as follows: Switches S2 and S3 are turned off, and braking energy is fed back to the battery side via VD1. Then, it flows through VD2 and VD3 through the excitation windings F1 and F2 to form a closed loop. In this mode, the battery acts as the excitation energy absorption source, causing the current i in the excitation winding to... f1 i f2 Decrease.

8. The control method for the integrated drive and charging system of a doubly salient pole motor current source type according to claim 2 or 3, characterized in that, When the system is running in charging mode Includes the following steps, Step A: Switches K1 and K2 are closed at point b, and the two excitation windings F1 and F2 are connected in reverse series, corresponding to the excitation current i. f1 and i f2 Equal in size and opposite in direction, i f1 =-i f2 To achieve the demagnetization function of the dual salient pole motor in charging mode, switch K3 is turned on to connect the three-phase armature winding of the dual salient pole motor to the AC power grid. At this time, the three-phase armature winding of the dual salient pole motor is reused as the filter inductor of the LC filter on the grid side. In step B, the switching transistors S1, S2, and S3 in the bidirectional charge-discharge converter are turned off, and the current source converter operates in rectification mode, transmitting electrical energy through VD1, VD2, and VD3 to charge the battery. Step C involves sampling the three-phase current of the motor using a downstream current sensor and determining the AC current angle on the grid side using a phase-locked loop (PLL) with the AC grid voltage. A dual closed-loop control strategy is adopted, combining the output DC current and AC current, to enable the current source converter to operate in rectifier mode and charge the battery according to the charging command.

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