CN201869109U - Digital medium-low frequency self-adaptive three-phase half-controlled rectifying device - Google Patents

Abstract

The utility model discloses a digital mid-low frequency self-adaptive three-phase half-control rectification device, which mainly includes a synchronous signal conditioning circuit, a digital control circuit and a pulse amplifying circuit. After the AC voltage signal is isolated by the optocoupler, it is sent to the digital control circuit through the conditioning circuit. The controller MCU calculates the period according to the synchronous signal sent in and updates the control angle to generate three trigger signals. The pulse amplifying circuit amplifies the signal and triggers the three-phase half-controlled bridge to realize controllable rectification. The method triggers the three phases sequentially according to the software program designed by the controller in the digital control circuit, compares the sampled voltage value with the preset voltage value, calculates the control angle through the PID digital controller, and realizes the closed-loop control of the rectified voltage. Beneficial effects of the utility model: the utility model realizes frequency self-adaptive digital phase-shift trigger rectification in the medium and low frequency voltage working range, has high output pulse symmetry, strong anti-interference ability, fast response speed, and simple synchronous signal conditioning circuit reliable features.

Description

Digital medium and low frequency adaptive three-phase half-controlled rectification device

technical field

The utility model belongs to the technical field of switchgear control for power electronic equipment, and mainly relates to a digital mid-low frequency self-adaptive three-phase half-control rectifier.

Background technique

When the alternating current output by the permanent magnet generator is not stabilized, when the load changes, the generator speed changes greatly, resulting in the amplitude and frequency of the three-phase alternating current generated by it changing within a wide range. In order to obtain a stable output voltage, a relatively stable DC voltage is generally obtained through controllable rectification and then inverted. However, the commonly used analog integrated trigger circuit is easily affected by various factors of power generation equipment. When the frequency changes greatly, the peripheral circuit parameters need to be adjusted, which makes the design complex and difficult to debug. The existing digital trigger circuit requires three synchronous signals as a reference for the controllable rectification of three-phase AC, and uses a synchronous transformer for isolation and phase matching, which requires heavy weight, many components and high cost.

Utility model content

The purpose of the utility model is to realize self-adaptive phase-shift trigger for low- and medium-frequency voltage input, simplify the synchronous sampling circuit, realize the anti-disturbance design combining software and hardware, and provide a digital Medium and low frequency adaptive three-phase half-controlled rectifier device and its triggering method.

产生a、b、c三路触发信号，其输出的信号经脉冲放大电路触发三相半控桥，数字控制电路的控制器MCU预先装入移相触发程序。The technical scheme adopted by the utility model to solve its technical problems: this digital mid-low frequency self-adaptive three-phase semi-controlled rectifier device includes a synchronous signal conditioning circuit, and the output signal is sent to the digital quantity input interface of the digital control circuit , used to measure the signal period and start the trigger signal; the digital control circuit includes the controller MCU, digital input interface circuit, digital output interface circuit and voltage sampling circuit, the controller MCU passes the PID digital The control angle calculated by the controller

Generate a, b, c three-way trigger signal, and the output signal triggers the three-phase half-controlled bridge through the pulse amplifier circuit, and the controller MCU of the digital control circuit is pre-loaded with a phase-shift trigger program.

The device can be used in the medium and low frequency range of 50Hz to 800Hz, and has frequency adaptability; the synchronous signal conditioning circuit has the function of initial phase setting and hardware anti-disturbance; at the same time, the digital control circuit can realize software anti-interference.

The beneficial effects of the utility model are: the utility model can monitor the cycle of the output voltage of the alternator in real time, remove the disturbance, and be capable of frequency self-adaptive phase-shift triggering in the working range of medium and low frequency voltages, directly sample from the side of the AC power supply and pass light The coupling isolation is used as the synchronous signal of the trigger circuit, and the synchronous transformer is omitted. Through software program design, only one synchronous signal conditioning circuit is needed. Because the function of the device is mainly realized by the digital control circuit, the phase-shift trigger is digitized, which is convenient for use, maintenance and adjustment.

Description of drawings

Fig. 1 is the system composition schematic diagram of the present utility model

Figure 2 is the waveform diagram of three-phase electric phase voltage and line voltage

Fig. 3 is the synchronous signal conditioning principle schematic diagram of the utility model

Fig. 4 is a schematic diagram of the edge cleaning sequence in the synchronous signal conditioning of the present invention

Fig. 5 is the principle schematic diagram of the pulse amplifying circuit of the present utility model

Fig. 6 is the program flowchart of the utility model controller

Fig. 7 is a schematic diagram of the controllable rectification of the PID digital controller used in the present invention.

Detailed ways

Below in conjunction with accompanying drawing and embodiment the utility model is further described:

产生a、b、c三路触发信号，其输出的信号经脉冲放大电路3触发三相半控桥4。工作时，交流电压信号由同步信号调理电路整形为同频率的方波信号，该输出送入数字控制电路的数字量输入接口电路，通过上升沿产生事件中断，通过控制器MCU捕捉两次上升沿的定时器值计算输入的信号频率。控制器MCU将计算的信号频率与工作频率范围比较，对异常扰动不动作。信号频率在有效工作频率范围内时，在捕捉事件发生后产生三相电的A相触发脉冲a，其移相角由反馈电压U_o与控制器程序中的的预设电压U_r通过PID数字控制器计算后修正。根据实时算得的同步信号周期T，输出延迟T/3的B相触发信号b和延迟2T/3的C相触发信号c。三路触发信号经脉冲放大电路隔离后触发三相半控桥4。The utility model discloses a digital mid-low frequency self-adaptive three-phase half-control rectification device. As shown in Figure 1, the device includes a synchronous signal conditioning circuit 1, and the output signal is sent to the digital input interface of the digital control circuit 2 for measuring the signal period and starting the trigger signal; the digital control circuit includes a controller MCU, Digital input interface circuit, digital output interface circuit and voltage sampling circuit, the controller MCU calculates the control angle through the PID digital controller according to the period of the synchronization signal and the error signal e

Three trigger signals a, b and c are generated, and the output signals are triggered by the pulse amplifying circuit 3 to trigger the three-phase half-controlled bridge 4 . When working, the AC voltage signal is shaped into a square wave signal of the same frequency by the synchronous signal conditioning circuit, and the output is sent to the digital input interface circuit of the digital control circuit, and the event interrupt is generated by the rising edge, and the rising edge is captured twice by the controller MCU The timer value counts the input signal frequency. The controller MCU compares the calculated signal frequency with the operating frequency range, and does not act on abnormal disturbances. When the signal frequency is within the effective working frequency range, a trigger pulse a of phase A of three-phase electricity is generated after the capture event occurs, and its phase shift angle is determined by the feedback voltage U _o and the preset voltage U _r in the controller program through the PID digital Correction after controller calculation. According to the synchronous signal cycle T calculated in real time, the B-phase trigger signal b delayed by T/3 and the C-phase trigger signal c delayed by 2T/3 are output. The three-way trigger signals trigger the three-phase half-controlled bridge 4 after being isolated by the pulse amplifier circuit.

As shown in Figure 2, the phase difference between the line voltage U _AC and the phase voltage U _A is 30°. In the implementation, the AC voltage signal U _AC is adjusted as the synchronous signal and then used as the initial phase reference of the A-phase trigger signal. When the control angle changes from 0° to 120°, a large-scale voltage regulation of the three-phase half-controlled rectification can be realized.

As shown in FIG. 3 , one AC voltage signal (AC-phase alternating current) is connected between the input terminals X1 and X2 of the optocoupler U1, and a diode D1 and a resistor R1 are connected in series at the input terminal. The output signal of the optocoupler passes through the integration circuit composed of transistors V1, V2, resistors R2, R3, R4, R5, R6, R7, diodes D2, D3, and capacitor C1, and the integrated signal A' and the output signal A of the optocoupler pass through or Device U2 gets an output signal Q ₀ :

Q ₀ ＝A or A'(1)

Adjusting the adjustable resistor R7 in the circuit shown in Figure 3 can change the time constant of the integration circuit of the synchronous signal. When the frequency is high, reduce the resistance value of R7, so that the time constant of the integral circuit decreases accordingly; when the frequency is low, increase the resistance value of R7, so that the time constant of the integral circuit increases accordingly.

The integrated signal A' and the optocoupler output signal A get the output signal CP through the device U3A:

CP=A and A'(2)

The output signal Q ₀ of the device U2 and the output signal CP of the device U3A are sent to the D flip-flop device U4, and the output signal Q ₁ is obtained as the input signal and the clock signal of U4 respectively:

Q ₁ ＝Q ₀ and CP↑(3)

Output signal Q ₀ of device U2 and output signal Q ₁ of device U4 are combined with device U3B to obtain output signal Q ₂ :

Q ₂ =Q ₀ and Q ₁ (4)

The output signal _Q2 of the device U3B is sent to the Schmitt trigger U5 to generate a synchronization signal.

As shown in Figures 4A to 4E, Figure 4A is the optocoupler output voltage signal waveform; Figure 4B is the voltage output waveform after the integration circuit; Figure 4C is the voltage output waveform after the OR circuit, and the optocoupler output is eliminated through the OR operation The trailing edge disturbance. Figure 4D is the voltage output waveform after passing through the AND circuit, and the leading edge disturbance of the optocoupler output is eliminated through the AND operation. FIG. 4E is the voltage waveform of the output of the D flip-flop after cleaning the front and rear edges.

As shown in Figure 5, the output signal of the digital control circuit is sent to the pulse amplifier circuit for amplification, and each phase amplifier circuit includes diode D1, resistors R1, R2, transistor V1, transformer T1, diodes D2, D3, resistors R3, R4 Pulse amplifier circuit. The trigger signal is amplified and output to the three-phase half-controlled bridge for phase-shift triggering.

The specific realization of the triggering method of the digital mid-low frequency self-adaptive three-phase half-controlled rectification is mainly carried out according to the following steps, and its control action flow is shown in Figure 6:

Step 1. Synchronous Signal Conditioning

a. The AC voltage signal output by the power generation equipment is isolated and output by the optocoupler to generate an approximate square wave signal;

b. The optocoupler output signal described in a is conditioned by the integration circuit and the front and rear edge cleaning circuits, and the synchronous signal generated is sent to the digital input interface of the digital control circuit;

c. According to the frequency range of the actual application, adjust the adjustable resistor R7 to change the time constant of the integrating circuit;

Step 2. Frequency adaptation and trigger pulse formation

a. The synchronous signal is sent to the digital input interface circuit of the digital control circuit. The CAP port of the controller MCU captures the rising edge of the synchronization signal, and generates a capture interrupt when the rising edge comes, and calculates the period T of the synchronization signal with the timer 3 count value between the two rising edges. Judging whether the measured signal period falls within the effective operating frequency range, and does not act on abnormal disturbances. When the synchronization signal cycle is valid, enable the trigger output;

b. Calculate the control angle according to the measured voltage signal period T as the trigger phase adjustment reference, and make a corresponding delay in the capture interrupt subroutine according to the calculated control angle, and generate the A-phase trigger signal from the I/O port of the controller, and start timer 1;

c. According to the phase characteristics of each phase of the three-phase AC, delay T/3 that is 120° after the A-phase trigger is generated, enter the timer 1 interrupt subroutine, and make a corresponding delay according to the control angle, which is generated by the I/O port of the controller Phase B trigger signal, and start timer 2, turn off timer 1;

d. According to the phase characteristics of each phase of the three-phase AC, delay T/3 or 120° after the B-phase trigger is generated, enter the timer 2 interrupt subroutine, and make a corresponding delay according to the control angle, which is generated by the I/O port of the controller Phase C trigger signal and turn off Timer 2:

e. When the three-phase alternating current signal is input in the next cycle, repeat steps a to d of step 2, and the initial phase and trigger control angle of each phase signal are updated immediately, and are synchronized with the input three-phase alternating current phase;

f. The output module of the digital control circuit generates three trigger signals, which are amplified by the pulse amplifier circuit to control the control angle of the three-phase half-controlled bridge;

As shown in Figure 7, it is a schematic diagram of the controllable rectification of the PID digital controller adopted by the utility model:

以快速跟踪频率不断变化的电压信号，改变三相半控桥的导通时刻，进而改变整流输出，实现对输出电压的闭环控制。g. The voltage sampling circuit samples the output voltage U _o after controllable rectification, and compares it with the preset voltage Ur in the controller program to obtain the deviation e through the PID digital controller to calculate the control angles of phase A, phase B and phase C. The calculated control angle is multiplied by the period compensation coefficient T2/T1 (T2 is the signal period value at the current moment, T1 is the signal period value at the previous moment) to get the actual control angle

By quickly tracking the voltage signal whose frequency is constantly changing, the conduction moment of the three-phase half-controlled bridge is changed, and then the rectified output is changed to realize the closed-loop control of the output voltage.

In summary, the utility model has the characteristics of self-adaptive frequency in the working range of medium and low frequency voltage, high output pulse symmetry, strong anti-interference ability, fast response speed and easy control. For the AC voltage signal that changes at any time in the medium and low frequency range, the digital control circuit calculates the control angle through the PID digital controller, and at the same time corrects the control angle with the signal period calculated in real time, so as to realize the self-adaptation to the medium and low frequency three-phase AC Controlled rectification.

Except for the above-mentioned embodiments, all technical solutions formed by equivalent replacement or equivalent transformation fall within the scope of protection required by the present utility model.

Claims (1)

1. digital medium and low frequency self adaptation three-phase half control rectifying device, it is characterized in that: this device comprises one tunnel synchronizing signal modulate circuit (1), the signal of its output is sent into the digital-quantity input interface of digital control circuit (2), is used for the measuring-signal cycle and starts triggering signal; Digital control circuit comprises controller MCU, digital-quantity input interface circuit, digital-quantity output interface circuit and voltage sampling circuit, the pilot angle that controller MCU calculates by the pid number controller according to the cycle and the error signal e of synchronizing signal

Produce a, b, c three tunnel triggering signals, the signal of its output triggers three-phase half controlled bridge (4) through pulse amplifying circuit (3).

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