Alternating current GCU voltage regulating circuit topology

Abstract

This invention belongs to the field of AC generator controller voltage regulation technology, and relates to an AC GCU voltage regulation circuit topology. It includes: a step-down transformer, a rectifier circuit, a circuit breaker, an excitation relay (GCR), a rectifier filter circuit, a sampling resistor, a MOSFET, a signal conditioning circuit, an excitation winding, and a freewheeling diode. The excitation winding is connected in series with the source of the MOSFET. A sampling resistor is added between the output of the rectifier filter circuit and the drain of the MOSFET. The voltage across the sampling resistor is detected. When the voltage across the sampling resistor rises to a threshold value, the GCR is disconnected, and the excitation is cut off to avoid system synchronization issues.

Description

Technical Field

[0001] This invention belongs to the field of AC generator controller voltage regulation technology, and relates to an AC GCU (generator controller) voltage regulation circuit topology. Background Technology

[0002] In a power supply system, the controller voltage regulation circuit is responsible for maintaining the generator output voltage within a specified range. Therefore, the controller voltage regulation circuit plays a crucial role in the power supply system.

[0003] Excitation control principle diagram as follows Figure 1 As shown, the working principle of excitation control is as follows: the three-phase AC power output from the permanent magnet generator inside the generator passes through the GCR (excitation relay) of the controller to the rectifier circuit. The rectified DC power is directly used as the positive excitation current and sent to one end of the generator excitation coil, while the other end of the generator excitation coil is fed back to the PWM voltage regulation control terminal of the controller. When the generator output voltage deviates from 115V, the PWM voltage regulation control signal controls the excitation current by controlling the on / off state of the MOSFET, thereby regulating the generator output voltage. The positive and negative terminals of the excitation relay GCR are controlled by the generator control switch GCS and the GCR control signal, respectively. When the generator control switch GCS is on and there is no fault in the main AC output, GCR is on. When the generator control switch GCS or the controller detects overvoltage, undervoltage, or other faults in the main AC output, GCR is off, cutting off the excitation.

[0004] Traditional analog AC voltage regulator circuit topology (excitation negative to ground short circuit) such as Figure 2 As shown. By Figure 2 It can be seen that when the excitation negative is short-circuited to ground, the MOSFET is not controlled by the PWM wave and is in a fully conducting state. At this time, the equivalent duty cycle is 1, the excitation current is the maximum, the POR voltage rises, and the system triggers overvoltage protection.

[0005] Traditional analog AC voltage regulator circuit topology (excitation positive short circuit to ground) such as Figure 3 As shown. By Figure 3It is known that when a short circuit occurs in the excitation coil, the TRU28V voltage will be pulled low during the short circuit. At this time, the voltage supplied to the positive terminal of the excitation relay GCR coil cannot maintain the contact engagement and will open. After the excitation relay GCR contacts open, the short circuit fault to ground in the excitation coil disappears, and the TRU28V voltage recovers. During this process, the GCS_INPUT signal jumps from a low level to 28V, so a reset signal is generated by the reset circuit. After software reset, it is re-initialized, and the voltage regulator, GCR, and MLC are controlled to disconnect. At this time, the TRU28V voltage returns to normal, the software detects that the GCS signal is valid, the generator speed meets the conditions for voltage establishment and grid connection, and controls the voltage regulator, GCR, and MLC to disconnect and engage. This cycle repeats, causing system disconnection and in turn causing the system to fail to generate electricity normally.

[0006] Traditional analog AC voltage regulator circuits can cause system overvoltage and system synchronization when an excitation-to-ground short circuit occurs, which is very harmful to the electrical load and the power supply system itself. Therefore, an AC GCU voltage regulator circuit topology was designed to avoid system overvoltage and system synchronization when the excitation-to-ground short circuit occurs. Summary of the Invention

[0007] Purpose of the invention: To propose an AC GCU voltage regulation circuit topology, which optimizes the traditional analog AC voltage regulation circuit topology and increases the sampling resistor to avoid system overvoltage faults and system synchronization faults when the excitation is short-circuited to ground.

[0008] Technical solution: An AC GCU voltage regulating circuit topology includes: a step-down transformer, a rectifier circuit, a circuit breaker, a magnetizing relay (GCR), a rectifier filter circuit, a sampling resistor, a MOSFET, a signal conditioning circuit, a magnetizing winding, and a freewheeling diode. The three-phase voltages of the permanent magnet generator are respectively input to the three input terminals of the step-down transformer and one end of the three contacts of the magnetizing relay (GCR). The output terminal of the step-down transformer is connected to the input terminal of the rectifier circuit; The output terminal of the rectifier circuit is connected to one end of the circuit breaker; the other end of the circuit breaker is connected to one end of the GCS switch, and the other end of the GCS switch is connected to the positive terminal of the excitation relay GCR coil. The GCR control signal is input to the negative terminal of the excitation relay GCR coil; The other ends of the three contacts of the excitation relay GCR are connected to the three input terminals of the rectifier filter circuit, respectively; the output terminal of the rectifier filter circuit is connected to one end of the sampling resistor. The other end of the sampling resistor is connected to the drain of the MOSFET. The generator voltage POR and the reference voltage are respectively input to the signal conditioning circuit, and the output of the signal conditioning circuit is connected to the gate of the MOSFET. The source of the MOSFET is connected to the negative terminal of the freewheeling diode and one end of the excitation winding, respectively. The positive terminal of the freewheeling diode and the other end of the excitation winding are grounded; The signal conditioning circuit is used to generate PWM waves.

[0009] Furthermore, the MOSFET is a WVM30N50 type MOSFET.

[0010] Furthermore, the sampling resistance is less than 1 ohm.

[0011] Furthermore, the rectifier filter circuit adopts a three-phase full-bridge filter circuit.

[0012] Furthermore, the rectifier circuit outputs a 28V DC voltage.

[0013] Furthermore, the PWM wave amplitude generated by the signal conditioning circuit is less than 15V.

[0014] Furthermore, the duty cycle of the PWM wave generated by the signal conditioning circuit is no greater than 70%.

[0015] Furthermore, the freewheeling diode is a 2CZ15CA type freewheeling diode.

[0016] Beneficial effects: This invention proposes an AC GCU voltage regulation circuit topology that optimizes the traditional analog voltage regulation circuit topology to avoid system overvoltage faults when the excitation is short-circuited to ground. A sampling resistor is added between the rectifier filter output and the drain of the MOSFET, and the voltage across the sampling resistor is detected. When the voltage across the sampling resistor rises to a threshold value, the GCR is disconnected and the excitation is cut off to avoid system synchronization issues. Attached Figure Description

[0017] Figure 1 This is the excitation control principle diagram; Figure 2 It is a traditional analog AC voltage regulator circuit topology (excitation negative short to ground). Figure 3 It is a traditional analog AC voltage regulator circuit topology (excitation positive short circuit to ground). Figure 4 It is an AC GCU voltage regulation circuit topology (excitation negative short to ground). Figure 5 It is an AC GCU voltage regulation circuit topology (excitation positive short to ground). Detailed Implementation

[0018] To avoid system overvoltage and system misalignment caused by excitation-to-ground short circuits, the traditional analog voltage regulator circuit topology is optimized by connecting the excitation winding in series with the source of the MOSFET, and adding a sampling resistor between the output of the rectifier filter circuit and the drain of the MOSFET. The rest of the voltage regulator circuit topology remains unchanged, resulting in an AC GCU voltage regulator circuit topology as follows: Figure 4 As shown.

[0019] An AC GCU voltage regulation circuit topology includes: a step-down transformer, a rectifier circuit, a circuit breaker, a GCS switch, a GCR, a rectifier filter circuit, a sampling resistor, a MOSFET, a signal conditioning circuit, a magnetizing winding, and a freewheeling diode.

[0020] The three-phase voltage of the permanent magnet generator is input to the three input terminals of the step-down transformer to reduce the three-phase voltage of the permanent magnet generator. The three output terminals of the step-down transformer are connected to the three input terminals of the rectifier circuit to rectify the three-phase AC power into DC voltage, and the DC voltage is 28V. The output terminal of the rectifier circuit is connected to one end of the circuit breaker. The other end of the circuit breaker is connected to one end of the GCS switch. The other end of the GCS switch is connected to the positive terminal of the excitation relay GCR coil to supply power to the GCR coil. The GCR control signal is input to the negative terminal of the excitation relay GCR coil.

[0021] The three-phase voltage of the permanent magnet generator is input to one end of the three contacts of the excitation relay GCR; the other ends of the three contacts of the excitation relay GCR are connected to the three input terminals of the rectifier and filter circuit, respectively. When the positive terminal of the GCR coil is 28V DC and the negative terminal of the coil receives a GCR control signal, the three contacts of the GCR close, inputting the three-phase voltage of the permanent magnet generator into the rectifier and filter circuit, which is a three-phase full-bridge rectifier circuit. The output terminal of the rectifier and filter circuit is connected to one end of a sampling resistor, and the other end of the sampling resistor is connected to the drain of a MOSFET. The sampling resistor is used to monitor the current in the branch where it is located. The resistance value of the sampling resistor is required to be less than 1 ohm to avoid excessive resistance, which would cause power loss.

[0022] The generator voltage POR and the reference voltage are input to the signal conditioning circuit, which generates a PWM wave to control the switching on and off of the MOSFET. The output of the signal conditioning circuit is connected to the gate of the MOSFET. The PWM wave generated by the signal conditioning circuit must have an amplitude of less than 15V and a duty cycle of no more than 70%. The source of the MOSFET is connected to the cathode of the freewheeling diode and one end of the excitation winding; the anode of the freewheeling diode and the other end of the excitation winding are grounded. The freewheeling diode is a 2CZ15CA type. This scheme is suitable for voltage regulation systems with an excitation current of less than 15A.

[0023] The generator's internal permanent magnet motor outputs three-phase AC power, which passes through the controller's GCR relay to the rectifier circuit. The rectified DC power is then connected to the drain of a MOSFET via a sampling resistor. The source of the MOSFET serves as the positive excitation current, supplying one end of the generator's excitation coil, while the other end of the excitation coil is connected to ground via the negative excitation current. When the generator output voltage deviates from 115V, the POR voltage and the reference voltage are used by a signal conditioning circuit to generate a PWM voltage regulation control signal. This signal controls the on / off state of the MOSFET to regulate the excitation current, thus achieving the generator output voltage regulation function. The positive and negative terminals of the excitation relay GCR are controlled by the generator control switch GCS and the GCR control signal, respectively. When the generator control switch GCS is on and there is no fault in the main AC output, GCR is on. When the generator control switch GCS or the controller detects overvoltage, undervoltage, or other faults in the main AC output, GCR is off, cutting off the excitation.

[0024] An AC GCU voltage regulation circuit topology (excitation negative to ground short circuit) is as follows: Figure 4 As shown. By Figure 2 It is known that when the excitation negative is short-circuited to ground, the excitation current is at its maximum in the traditional analog AC voltage regulator circuit topology, the POR voltage rises, and the system triggers overvoltage protection. Figure 4 It can be seen that since the excitation negative of the GCU voltage regulating circuit topology is connected to the ground wire, there is no excitation negative to ground short circuit fault. This fault phenomenon does not exist and will not cause the system to trigger overvoltage protection.

[0025] An AC GCU voltage regulation circuit topology (excitation positive short to ground) is as follows: Figure 5 As shown. By Figure 5 It is known that when the excitation positive voltage is short-circuited to ground, the excitation positive voltage is pulled down, the three-phase voltage of the permanent magnet generator is pulled down, and the TRU28V voltage is also pulled down. According to the excitation control principle, the TRU28V voltage is supplied to the positive terminal of the GCR coil through the circuit breaker and GCS switch. When the TRU28V voltage is pulled down, the voltage supplied to the positive terminal of the excitation relay GCR coil cannot maintain contact engagement and thus opens. After the excitation relay GCR contacts open, the excitation positive voltage short-circuit fault to ground disappears, the three-phase voltage of the permanent magnet generator recovers, the TRU28V voltage recovers, and the voltage supplied to the positive terminal of the excitation relay GCR coil recovers, the GCR is activated, the generator speed meets the conditions for voltage establishment and grid connection, and the voltage regulator, GCR, and MLC are activated. When the GCR is activated, the excitation positive voltage is pulled down, and the three-phase voltage of the permanent magnet generator is pulled down, affecting subsequent circuits. This cycle repeats, causing system disconnection, which in turn leads to the system's inability to generate electricity normally.

[0026] To solve the above system synchronization problem, such as Figure 5As shown, a sampling resistor is added between the output of the rectifier filter circuit and the drain of the MOSFET. The resistance of the sampling resistor must be less than 1 ohm to avoid excessive resistance causing power loss in the excitation circuit. The current in the branch containing the sensitive sampling resistor is monitored, and the voltage across the sampling resistor is acquired. The real-time voltage value across the sampling resistor is then sent to the CPU board for monitoring via a signal sampling circuit. When the excitation circuit is short-circuited to ground, the signal is transmitted through the sampling circuit. Figure 5 Analysis shows that the voltage across the sampling resistor will increase. At this time, the CPU detects that the voltage across the sampling resistor has increased. When the voltage across the sampling resistor reaches the specified threshold, it identifies that a short circuit fault has occurred between the excitation and ground, and then disconnects the GCR and cuts off the excitation to avoid causing system failure.

Claims

1. A topology for an AC GCU voltage regulation circuit, characterized in that, include: The circuit includes a step-down transformer, a rectifier circuit, a circuit breaker, a magnetizing relay (GCR), a rectifier filter circuit, a sampling resistor, a MOSFET, a signal conditioning circuit, a magnetizing winding, and a freewheeling diode. The three-phase voltages of the permanent magnet generator are respectively input to the three input terminals of the step-down transformer and one end of the three contacts of the magnetizing relay (GCR). The output terminal of the step-down transformer is connected to the input terminal of the rectifier circuit; The output terminal of the rectifier circuit is connected to one end of the circuit breaker; the other end of the circuit breaker is connected to one end of the GCS switch, and the other end of the GCS switch is connected to the positive terminal of the excitation relay GCR coil. The GCR control signal is input to the negative terminal of the excitation relay GCR coil; The other ends of the three contacts of the excitation relay GCR are connected to the three input terminals of the rectifier filter circuit, respectively; the output terminal of the rectifier filter circuit is connected to one end of the sampling resistor. The other end of the sampling resistor is connected to the drain of the MOSFET. The generator voltage POR and the reference voltage are respectively input to the signal conditioning circuit, and the output of the signal conditioning circuit is connected to the gate of the MOSFET. The source of the MOSFET is connected to the negative terminal of the freewheeling diode and one end of the excitation winding, respectively. The positive terminal of the freewheeling diode and the other end of the excitation winding are grounded; The signal conditioning circuit is used to generate PWM waves; The voltage across the sampling resistor is monitored. When the voltage across the sampling resistor rises to the threshold value, the excitation relay GCR is disconnected and the excitation is cut off to avoid system synchronization issues.

2. The AC GCU voltage regulation circuit topology according to claim 1, characterized in that, The MOSFET is a WVM30N50 type MOSFET.

3. The AC GCU voltage regulation circuit topology according to claim 1, characterized in that, The sampling resistor is less than 1 ohm.

4. The AC GCU voltage regulation circuit topology according to claim 1, characterized in that, The rectifier filter circuit adopts a three-phase full-bridge filter circuit.

5. The AC GCU voltage regulation circuit topology according to claim 1, characterized in that, The rectifier circuit outputs 28V DC.

6. The AC GCU voltage regulation circuit topology according to claim 1, characterized in that, The amplitude of the PWM wave generated by the signal conditioning circuit is less than 15V.

7. The AC GCU voltage regulation circuit topology according to claim 1, characterized in that, The duty cycle of the PWM wave generated by the signal conditioning circuit is no greater than 70%.

8. The AC GCU voltage regulation circuit topology according to claim 1, characterized in that, The freewheeling diode is a 2CZ15CA type freewheeling diode.

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