A permanent magnet synchronous generator system power following system and a control method thereof

Abstract

The application discloses a permanent magnet synchronous generator system power following system and a control method thereof, and relates to the technical field of power generation control. The method comprises the following steps: 1, obtaining the maximum current of the current power battery charging current and the power consumption of the load system, respectively; calculating the discharging current of the power battery according to the DC side voltage obtained by current sampling, and adding the maximum current of the current power battery charging current to the discharging current to obtain the actual charging current instruction; 2, sampling the actual charging current of the power battery, namely the load current. The power following control method provided by the application can dynamically adjust the charging power and the charging current of the power battery according to the temperature and the state of charge of the power battery and the actual power consumption demand of the load system, improves the charging speed of the power battery under the premise of ensuring safety, and does not need the intervention of the vehicle controller, thereby simplifying the complexity of the vehicle control.

Description

Technical Field

[0001] This invention relates to the field of power generation control technology, and in particular to a power following system for a permanent magnet synchronous generator system and its control method. Background Technology

[0002] Range-extended electric vehicles (REEVs) are created by adding a range extender to a pure electric vehicle to address the short driving range of existing pure electric vehicles. When the state of charge (SOC) of the battery is low, the range extender charges the battery. The range extender consists of an engine, a permanent magnet synchronous generator, and a PWM rectifier.

[0003] Charging power batteries requires ensuring both speed and safety during the charging process, and avoiding phenomena such as battery overheating and overcharging.

[0004] Existing charging control strategies generally adopt the power follower mode. The power follower mode uses the maximum allowable charging current of the power battery as the benchmark for closed-loop control of the power generation. It obtains the actual charging and discharging current of the power battery through the CAN bus and performs closed-loop control. The advantage is that it can dynamically limit the charging current according to the temperature of the power battery, thereby improving the service life of the power battery. The disadvantage is that it does not consider the power demand of the load system, resulting in slow charging of the power battery and problems such as incomplete charging. Summary of the Invention

[0005] The main objective of this invention is to provide a power following system for a permanent magnet synchronous generator system and its control method, in order to overcome the problem that the existing technology does not consider the power demand of the load system during the charging process of the power battery, resulting in slow charging of the power battery. Furthermore, it solves the problem that the existing technology requires the intervention of the vehicle controller during the charging process of the power battery, and the vehicle controller issues a power generation command based on the state of the power battery, which makes the control of the vehicle controller complicated.

[0006] The objective of this invention can be achieved by adopting the following technical solution:

[0007] A power following control method for a permanent magnet synchronous generator system includes the following steps:

[0008] Step 1: Obtain the current maximum charging current of the power battery and the power consumption of the load system respectively. Calculate the discharge current of the power battery based on the DC side voltage obtained from the current sampling. Add the current maximum charging current of the power battery to the discharge current to obtain the actual charging current command.

[0009] Step 2: Sample the actual charging current of the power battery, i.e. the load current, calculate the difference between the power battery charging current command and the load current, and output the power generation command through the PI regulator and the limiting module.

[0010] Step 3: Obtain the engine speed command based on the power generation command and the power-engine speed curve, and control the engine speed via the CAN bus;

[0011] The torque command of the permanent magnet synchronous generator is obtained based on the power generation command and the power-motor torque curve, and the torque control of the permanent magnet synchronous generator is realized through the current closed loop.

[0012] The current closed loop in step 3 is specifically as follows:

[0013] The AC and DC axis current commands of the permanent magnet synchronous motor are obtained by looking up the table based on the torque command and the motor's torque-current curve.

[0014] The difference between the AC and DC axis current commands and the corresponding feedback values ​​is used to obtain the AC and DC axis voltage commands through a PI regulator.

[0015] The AC and DC axis voltage commands are processed by the space voltage vector modulation module to obtain the control signal of the switching transistor, so as to realize the dynamic control of the charging power of the power battery.

[0016] Preferably, in step 1, the temperature and state of charge of the power battery are obtained through the CAN bus, and then the maximum value of the current power battery charging current is obtained according to the charge and discharge characteristic curve provided by the power battery manufacturer.

[0017] Preferably, in step 2,

[0018] If the input to the limiting module is less than zero, the output of the limiting module will be zero, that is, the power generation command will be zero.

[0019] If the input of the limiting module is greater than zero and not greater than the maximum power output of the permanent magnet synchronous generator, then the input of the limiting module is directly output, that is, the power output command is directly the output of the PI regulator.

[0020] If the input of the limiting module is greater than zero and greater than the maximum power output of the permanent magnet synchronous generator, then the output of the limiting module is the maximum power output, that is, the power output command is the maximum power output of the permanent magnet synchronous generator.

[0021] A power follower system for a permanent magnet synchronous generator system includes an engine, a permanent magnet synchronous generator, a rotary transformer for acquiring rotor position signals of the motor, a three-phase full-bridge main power circuit, a power battery, a load system, current sensors for acquiring the three-phase armature winding current and load current of the motor, and a power generation control unit for controlling the engine speed and the torque of the permanent magnet synchronous generator based on the detected variables.

[0022] Beneficial technical effects of the present invention:

[0023] The power following control method provided by this invention can dynamically adjust the charging power and charging current of the power battery according to the temperature and state of charge of the power battery and the actual power demand of the load system. It improves the charging speed of the power battery while ensuring safety, and simplifies the complexity of vehicle control without the intervention of the vehicle controller. Attached Figure Description

[0024] Figure 1 This is a block diagram of the permanent magnet synchronous generator system of the present invention;

[0025] Figure 2 This is a schematic diagram of the power generation control unit;

[0026] Figure 3 This is a schematic diagram of the current loop control principle.

[0027] Explanation of the labels in the diagram: T1, T2, T3, T4, T5, and T6 are switching transistors with anti-parallel diodes; C1 is the DC-side filter capacitor; H... a H b H c H L Hall current sensor;

[0028] i a i b i c The three-phase armature current is θ, the rotor position angle is ω. e U is the rotor's electric angular velocity. dcfdb The measured DC-side voltage;

[0029] Temp is the temperature of the power battery, SOC is the state of charge of the power battery, and i cha i represents the maximum charging current of the power battery. L Let i be the load current. L1 i is the discharge current of the power battery. Lcmd The charging current command for the power battery, Δi L The difference between the power battery charging current command and the load current.

[0030] P pre For the power generation request before the throttling, P cmd For the actual power generation command, P max The maximum generating power of the permanent magnet synchronous generator is given by T, where EngSpd is the engine speed command and T is the maximum generating power of the permanent magnet synchronous generator. cmd This is the torque command for the permanent magnet synchronous generator;

[0031] i qfdb i dfdb i represents the feedback values ​​of the AC and DC axis currents in the three-phase windings. qref i dref These are the commanded values ​​for the AC and DC axis currents;

[0032] Δi q , Δi d The difference between the direct and quadrature axis current command value and the feedback value; U q U d These are the AC and DC axis voltage command values, respectively. Detailed Implementation

[0033] To enable those skilled in the art to understand the technical solution of the present invention more clearly, the present invention will be further described in detail below with reference to the embodiments and accompanying drawings, but the embodiments of the present invention are not limited thereto.

[0034] like Figures 1-3 As shown, the power following control method for a permanent magnet synchronous generator system provided in this embodiment includes the following steps:

[0035] The engine drives the permanent magnet synchronous generator to rotate, and the three-phase full-bridge main power circuit converts the three-phase AC power into DC power to charge the power battery.

[0036] The battery temperature (Temp) and state of charge (SOC) are obtained via the CAN bus. The maximum current (i) of the current battery charging current is then determined by referring to a table based on the battery charge / discharge characteristic curve provided by the manufacturer. cha ;

[0037] The power consumption of the load system is obtained through the CAN bus, and the discharge current i of the power battery is calculated based on the currently sampled DC-side voltage. L1 i cha Add i L1 This refers to the actual power battery charging current command i Lcmd ;

[0038] i Lcmd The actual charging current i obtained by sampling L The difference is calculated, and the difference value is processed by the PI regulator and the limiting module to output the actual power generation command P. cmd ;

[0039] Where, if P pre If P is less than zero, then cmd It equals zero;

[0040] If P pre Greater than zero and greater than P max Then P cmd equals P max ;

[0041] If P pre Greater than zero and less than P max Then P cmd equals P pre ;

[0042] According to the actual power generation command P cmd The engine speed command EngSpd and the permanent magnet synchronous generator torque command T are obtained by looking up the power-engine speed curve and the power-motor torque curve, respectively. cmd ;

[0043] Finally, the engine torque is controlled via the CAN bus, and the torque of the permanent magnet synchronous generator is controlled via a current closed loop.

[0044] The current closed-loop control is specifically as follows:

[0045] First, according to the torque command T cmd The AC and DC axis current commands i of the permanent magnet synchronous motor are obtained by looking up the torque-current curve of the motor in a table. qref i dref ;

[0046] Then, the AC and DC axis current commands are respectively compared with the feedback value i qfdb i dfdb The difference is calculated and passed through a PI controller to obtain the direct and quadrature axis voltage command U. q U d ;

[0047] Finally, the AC and DC axis voltage commands are processed by the space vector voltage modulation module (SVPWM) to obtain the control signal for the switching transistor, thereby realizing the dynamic control of the charging power of the power battery.

[0048] A power tracking system for a permanent magnet synchronous generator includes an engine, a permanent magnet synchronous generator, a rotary transformer for acquiring rotor position signals, a three-phase full-bridge main power circuit, a power battery, a load system, current sensors for acquiring three-phase armature winding current and load current, and a power generation control unit for controlling the engine speed and permanent magnet synchronous generator torque based on the detected variables. The control unit includes a PI regulator, a coordinate transformation module, a space voltage vector modulation module, a limiting module, and a current loop control unit. Figures 2-3 As shown.

[0049] In summary, in this embodiment, the power following control method can dynamically adjust the charging power and charging current of the power battery according to the temperature and state of charge of the power battery and the actual power demand of the load system. It improves the charging speed of the power battery while ensuring safety, and simplifies the complexity of vehicle control without the intervention of the vehicle controller.

[0050] The above description is merely a further embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope disclosed in the present invention, based on the technical solution and concept of the present invention, shall fall within the scope of protection of the present invention.

Claims

1. A power following control method for a permanent magnet synchronous generator system, characterized in that: Includes the following steps Step 1: Obtain the current maximum charging current of the power battery and the power consumption of the load system respectively. Calculate the discharge current of the power battery based on the DC side voltage obtained from the current sampling. Add the current maximum charging current of the power battery to the discharge current to obtain the actual charging current command. Step 2: Sample the actual charging current of the power battery, i.e. the load current, calculate the difference between the power battery charging current command and the load current, and output the power generation command through the PI regulator and the limiting module. Step 3: Obtain the engine speed command based on the power generation command and the power-engine speed curve, and control the engine speed via the CAN bus; The torque command of the permanent magnet synchronous generator is obtained based on the power generation command and the power-motor torque curve, and the torque control of the permanent magnet synchronous generator is realized through the current closed loop. The current closed loop in step 3 is specifically as follows: The AC and DC axis current commands of the permanent magnet synchronous motor are obtained by looking up the table based on the torque command and the motor's torque-current curve. The difference between the AC and DC axis current commands and the corresponding feedback values ​​is used to obtain the AC and DC axis voltage commands through a PI regulator. The AC and DC axis voltage commands are processed by the space voltage vector modulation module to obtain the control signal of the switching transistor, so as to realize the dynamic control of the charging power of the power battery.

2. The power following control method for a permanent magnet synchronous generator system according to claim 1, characterized in that: In step 1, the temperature and state of charge of the power battery are obtained through the CAN bus, and then the maximum value of the current charging current of the power battery is obtained according to the charge and discharge characteristic curve provided by the power battery manufacturer.

3. The power following control method for a permanent magnet synchronous generator system according to claim 1, characterized in that: In step 2, If the input to the limiting module is less than zero, the output of the limiting module will be zero, that is, the power generation command will be zero. If the input of the limiting module is greater than zero and not greater than the maximum power output of the permanent magnet synchronous generator, then the input of the limiting module is directly output, that is, the power output command is directly the output of the PI regulator. If the input of the limiting module is greater than zero and greater than the maximum power output of the permanent magnet synchronous generator, then the output of the limiting module is the maximum power output, that is, the power output command is the maximum power output of the permanent magnet synchronous generator.

4. A power follower system for a permanent magnet synchronous generator system, characterized in that: The system includes an engine, a permanent magnet synchronous generator, a rotary transformer for acquiring rotor position signals, a three-phase full-bridge main power circuit, a power battery, a load system, current sensors for acquiring three-phase armature winding current and load current, and a power generation control unit for controlling the engine speed and the torque of the permanent magnet synchronous generator based on the detected variables. The permanent magnet synchronous generator system power following system is used to implement the permanent magnet synchronous generator system power following control method as described in any one of claims 1 to 3.

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