Control circuit based on generator ISG

Abstract

The invention provides a control circuit based on a generator ISG, and relates to the technical field of generators. The control circuit based on the generator ISG comprises a three-phase rectifier bridge which connects three-phase output ends U, V and W of the generator to midpoints of bridge arms through body diodes and is used for converting alternating current into direct current and charging a bus capacitor C; the bus capacitor C is connected to the output end of the rectifier bridge and is used for storing electric energy and smoothly outputting direct-current voltage; and the load resistor R1 is connected to the rear end of the bus capacitor and consumes the output power of the circuit. According to the control circuit based on the generator ISG, the ISG effectively stabilizes the bus voltage and reduces the voltage overshoot risk through FOC control when the generator is suddenly unloaded, meanwhile, the capacity requirement of a bus capacitor can be reduced, and therefore the hardware cost is reduced, and the system response speed is increased.

Description

Technical Field

[0001] The present invention relates to the technical field of generators, and in particular to a control circuit based on a generator ISG. Background Art

[0002] Generators are key equipment that are widely used in power systems, industrial production, emergency rescue, and mobile power sources by converting mechanical energy into electrical energy. The working principle is based on electromagnetic induction, which generates current through the relative movement of a rotating magnetic field and a conductor. Generators not only support the stable operation of power networks, but also provide backup power when the mains is interrupted, ensuring the continuous operation of key equipment. In addition, it maintains the operation of production lines in industrial applications, provides traction in railway and ship power systems, and acts as a mobile power source in areas with unstable power or field operations, providing indispensable support for the power needs of modern society.

[0003] ISG can be widely used in generator software. The traditional permanent magnet synchronous generator charges the electricity generated by the generator into the bus capacitor, and then controls the hardware through software to perform inversion, boost, and voltage reduction. If the generator is not loaded, the voltage of the bus capacitor is very stable, but once the generator starts to be loaded, the bus capacitor voltage will drop. At this time, the output power of the generator will drop. For this reason, the speed of the generator needs to be increased to obtain higher input power and increase the bus voltage to the rated voltage. Therefore, many generator software also need to control the generator throttle. In the case of sudden unloading of the generator, due to the inertia of the generator rotor, the software cannot reduce the speed of the generator in time, resulting in excessive input voltage, which in turn causes excessive bus voltage and damage to the bus capacitor. Summary of the invention

[0004] In view of the shortcomings of the prior art, the present invention provides a control circuit based on the generator ISG, which solves the problem that in a traditional permanent magnet synchronous generator, when the generator starts to be loaded, the voltage of the bus capacitor will drop, resulting in a decrease in the generator output power. This requires increasing the generator speed to maintain the bus voltage, and in the case of sudden unloading of the generator, due to the inertia of the generator rotor, the software cannot quickly reduce the generator speed, resulting in an excessively high input voltage, which may cause the bus voltage to be too high, thereby damaging the bus capacitor.

[0005] To achieve the above objectives, the present invention is implemented through the following technical solutions: A control circuit based on a generator ISG, comprising: a three-phase rectifier bridge, which connects the three-phase output terminals U, V, and W of the generator to the midpoint of the bridge arm respectively through a body diode, and is used to convert AC power into DC power and charge the bus capacitor C;

[0006] The bus capacitor C is connected to the output end of the rectifier bridge to store electrical energy and smooth the output DC voltage;

[0007] The load resistor R1 is connected to the rear end of the bus capacitor and consumes the output power of the circuit;

[0008] The dual-resistance sampling module is used to sample the current when the lower bridge (Q2, Q4, Q6) is fully open to obtain the generator current information and minimize the current interference;

[0009] Clarke transformation module, used to transform the sampled current into an α-β coordinate system;

[0010] The sliding membrane observer uses the current data transformed by Clarke to observe the electrical angle of the motor in real time;

[0011] The PI controller, in the FOC framework, receives the set I d_ref and Iq_ref, wherein Iq_ref is set to zero, and I d_ref is adjusted to generate a flux opposite to the flux of the permanent magnet, and the bus voltage stabilization control is achieved by adjusting Id_ref;

[0012] Park inverse transformation module, used to convert the current regulation value output by the PI controller into control voltages Uα and Uβ;

[0013] The SVPWM vector control unit generates PWM signals based on Uα and Uβ to adjust the motor operation and control the stability of the bus voltage;

[0014] The voltage monitoring and regulation module intervenes by adjusting Id_ref when it detects that the bus voltage exceeds a predetermined threshold (rated voltage plus 20V) to achieve closed-loop stable control of the bus voltage;

[0015] The running sequence control module operates continuously through electrical angle detection and the voltage PI loop of the PI controller since the generator starts, especially when the generator is suddenly unloaded from full load or heavy load, the bus voltage is ensured to remain stable by increasing the three-phase bridge current.

[0016] Preferably, the dual-resistance sampling module is sampled by the current in the case of inductor freewheeling inside the generator to ensure minimum interference with the sampled current.

[0017] Preferably, the voltage monitoring and regulation module uses a voltage PI control loop to compare the bus voltage feedback with the target voltage and adjust the Id_ref value accordingly.

[0018] Preferably, the motor induction flux is adjusted when the generator is suddenly unloaded to reduce the magnetic induction of the rotor cutting, thereby achieving a voltage regulation effect.

[0019] Preferably, the SVPWM vector control module uses the generated Uα and Uβ to generate an accurate PWM signal to achieve torque regulation of the motor output.

[0020] The present invention provides a control circuit based on a generator ISG, which has the following beneficial effects:

[0021] The present invention provides a control circuit based on the generator ISG. The present invention is controlled by software and does not need to consider the inertia of the rotor. It can respond to system changes very quickly. When the generator is suddenly unloaded, the dual-resistance sampling FOC control of the ISG software can effectively alleviate and stabilize the bus voltage fluctuation, prevent voltage overshoot, and thus protect the bus capacitor from damage. Since the bus voltage can be better controlled, the large-capacity demand for the bus capacitor is reduced, thereby reducing the hardware cost. The closed-loop control of the bus voltage is achieved through the given Id_ref and Iq_ref, which effectively reduces the interference and instability during voltage stabilization. The FOC control method can be used to flexibly adjust and optimize the operating state of the motor and improve the operating efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 Schematic diagram of the control topology of the present invention. DETAILED DESCRIPTION

[0023] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0024] like Figure 1 As shown, an embodiment of the present invention provides a control circuit based on a generator ISG, including: a three-phase rectifier bridge, which connects the three-phase output terminals U, V, and W of the generator to the midpoint of the bridge arm respectively through a body diode, so as to convert AC power into DC power and charge the bus capacitor C;

[0025] The bus capacitor C is connected to the output end of the rectifier bridge to store electrical energy and smooth the output DC voltage;

[0026] The load resistor R1 is connected to the rear end of the bus capacitor and consumes the output power of the circuit;

[0027] The dual-resistance sampling module is used to sample the current when the lower bridge (Q2, Q4, Q6) is fully open to obtain the generator current information and minimize the current interference;

[0028] Clarke transformation module, used to transform the sampled current into an α-β coordinate system;

[0029] The sliding membrane observer uses the current data transformed by Clarke to observe the electrical angle of the motor in real time;

[0030] The PI controller, in the FOC framework, receives the set I d_ref and I q_ref, wherein I q_ref is set to zero, and I d_ref is adjusted to generate a magnetic flux opposite to the magnetic flux of the permanent magnet, and the bus voltage stabilization control is achieved by adjusting I d_ref;

[0031] Park inverse transformation module, used to convert the current regulation value output by the PI controller into control voltages Uα and Uβ;

[0032] The SVPWM vector control unit generates PWM signals based on Uα and Uβ to adjust the motor operation and control the stability of the bus voltage;

[0033] The voltage monitoring and regulation module intervenes by adjusting I d_ref when it detects that the bus voltage exceeds a predetermined threshold (rated voltage plus 20V) to achieve closed-loop stable control of the bus voltage;

[0034] The running sequence control module operates continuously through electrical angle detection and the voltage PI loop of the PI controller since the generator starts, especially when the generator is suddenly unloaded from full load or heavy load, the bus voltage is ensured to remain stable by increasing the three-phase bridge current.

[0035] The dual-resistance sampling module samples the current when the inductor continues to flow inside the generator to ensure minimum interference with the sampled current. The voltage monitoring and regulation module uses a voltage PI control loop to compare the bus voltage feedback with the target voltage and adjusts the I d_ref value accordingly. The motor induction flux is adjusted when the generator is suddenly unloaded to reduce the magnetic induction of the rotor cutting, thereby achieving voltage regulation. The SVPWM vector control module uses the generated Uα and Uβ to generate precise PWM signals to achieve torque regulation of the motor output.

[0036] Specifically, the ISG software design concept of the present invention uses the FOC principle for control. Figure 1 In the figure, U, V, and W are connected to the three-phase input terminals of the motor respectively, Q1, Q2, Q3, Q4, Q5, and Q6 are used as three-phase rectifier bridges, and the three phases of the U, V, and W motors are connected to the midpoints of the three-phase rectifier bridge arms respectively. The rectifier bridge is connected to the bus capacitor C, and R1 is the load.

[0037] Depend on Figure 1It can be seen that when the generator is generating electricity, the uncontrolled switching tube can also be used to charge the bus capacitor through uncontrolled rectification through the body diode. However, this also causes the motor speed to fail to drop quickly when the generator is suddenly unloaded, causing damage to the bus capacitor or even explosion.

[0038] The present invention adopts a dual-resistance sampling FOC control method, which performs current sampling when the lower bridge (Q2, Q4, Q6) is fully open. At this time, the current is freewheeling through the internal inductance of the generator. The current interference generated at this time is minimal and the most "clean". The current is brought into the sliding film observer after Clarke transformation to observe the electrical angle of the motor, and then the set Id_ref and Iq_ref are controlled by PI, and then the electrical angle is inversely transformed with Park to obtain Uα and Uβ. Finally, SVPWM vector control is performed according to Uα and Uβ to perform PWM wave generation to generate corresponding torque to drive the motor to rotate. However, the torque of the generator at this time comes from the internal combustion engine. The given Iq_ref is set to 0 and I By setting d_ref to an appropriate value, through internal closed-loop control, the magnetic induction ability of the rotor cutting can be reduced by changing the motor inductance vector to generate a magnetic flux opposite to the permanent magnet magnetic flux. From E=BLv (B represents the magnetic induction intensity, L represents the conductor length, and v represents the movement speed of the conductor in the magnetic field), it can be seen that when B is reduced, the voltage generated will be reduced when the generator speed remains unchanged. Therefore, by controlling the size of the given Id_ref in FOC, closed-loop control of the bus voltage stabilization can be achieved. When the generator is suddenly unloaded from full load or heavy load, its specific working sequence is as follows: the arc detection has been running at startup. When it is detected that the bus voltage exceeds the rated 20V, the ISG will intervene. The target bus voltage is given and the current bus voltage uses the voltage as a PI loop, and the data is given to the Id_ref given by the FOC. Then the detected current is observed for electrical angle and the Id after C l arke transformation is PI controlled with the given Id_ref, and then Uα and Uβ are generated after PI transformation with the observed electrical angle and Park inverse transformation. Finally, Uα and Uβ are used for Svpwm vector PWM calculation, which will eventually increase the three-phase bridge current and finally achieve bus voltage stability.

[0039] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A control circuit based on a generator ISG, characterized in that: include: A three-phase rectifier bridge, which connects the three-phase output terminals U, V, and W of the generator to the midpoint of the bridge arm through body diodes, for converting AC power into DC power and charging the bus capacitor C; The bus capacitor C is connected to the output end of the rectifier bridge to store electrical energy and smooth the output DC voltage; The load resistor R1 is connected to the rear end of the bus capacitor and consumes the output power of the circuit; The dual-resistance sampling module is used to sample the current when the lower bridge (Q2, Q4, Q6) is fully open to obtain the generator current information and minimize the current interference; Clarke transformation module, used to convert the sampled current into the α-β coordinate system; The sliding film observer uses the current data after Clarke transformation to observe the electrical angle of the motor in real time; The PI controller, in the FOC framework, receives the set Id_ref and Iq_ref, where Iq_ref is set to zero and Id_ref is adjusted to produce a flux opposite to the flux of the permanent magnet, and the bus voltage stabilization control is achieved by adjusting Id_ref; Park inverse transformation module, used to convert the current regulation value output by the PI controller into control voltages Uα and Uβ; The SVPWM vector control unit generates PWM signals based on Uα and Uβ to adjust the motor operation and control the stability of the bus voltage; The voltage monitoring and regulation module intervenes by adjusting Id_ref when it detects that the bus voltage exceeds a predetermined threshold (rated voltage plus 20V) to achieve closed-loop stable control of the bus voltage; The running sequence control module operates continuously through electrical angle detection and the voltage PI loop of the PI controller since the generator starts, especially when the generator is suddenly unloaded from full load or heavy load, the bus voltage is ensured to remain stable by increasing the three-phase bridge current.

2. A control circuit based on a generator ISG according to claim 1, characterized in that: The dual-resistance sampling module is sampled by the current in the case of freewheeling of the inductor inside the generator to ensure minimum interference of the sampled current.

3. A control circuit based on a generator ISG according to claim 1, characterized in that: The voltage monitoring and regulation module uses a voltage PI control loop to compare the bus voltage feedback with the target voltage and adjust the Id_ref value accordingly.

4. A control circuit based on a generator ISG according to any one of claims 1 to 3, characterized in that: By adjusting the motor induction flux linkage when the generator is suddenly unloaded, the magnetic induction of the rotor cutting is reduced, thereby achieving a voltage regulation effect.

5. A control circuit based on a generator ISG according to claim 1, characterized in that: The SVPWM vector control module uses the generated Uα and Uβ to generate an accurate PWM signal to achieve torque regulation of the motor output.

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