CN203151389U - Control circuit of three-phase high power factor rectifier - Google Patents

Abstract

The utility model discloses a control circuit of a three-phase high power factor rectifier, and belongs to the field of electric control. The control circuit comprises an input high-frequency filter circuit, a three-phase input inductor and a three-phase rectifier circuit, and also comprises a switching tube power circuit, an output rectification filter circuit, a voltage dividing detection circuit, an input current detection unit, a single cycle controller and a switching tube drive circuit. The control circuit of the three-phase high power factor rectifier can realize three-phase high power factor rectification, can obtain steady-state output voltage of relatively high precision, and has a strong anti-interference capability.

Description

A control circuit of a three-phase high power factor rectifier

technical field

The invention relates to the field of electrical control, and more specifically relates to a rectifier which uses a single-cycle single-phase PFC chip to control a decoupled three-phase circuit and realizes three-phase high power factor input.

Background technique

With the development of the national economy, there are more and more various electrical equipment. Since the input of most electrical equipment adopts non-controllable rectification, the harmonic content of the input terminal current of electrical equipment is very high, which brings a lot of "harmonic pollution" to the power grid and increases the loss of the power grid. In order to reduce the harmonic pollution and electromagnetic interference of the device to the power grid, a corresponding harmonic suppression method and a power factor correction circuit are proposed. Therefore, it is necessary to add a power factor correction (Power Factor Correction, PFC) device to the input of the electrical equipment. Reduce input harmonic pollution and improve power factor. The research on single-phase PFC technology has been very mature, and there are many integrated control chips, such as UC3854, IRll50S, LTl508, ML4819, etc., and the three-phase PFC rectifier has more advantages: (1) Higher input power, up to (2) The sum of the pulsation of the three-phase input power is zero, while the pulsation of the output power is one-third of that of the single-phase, the output capacitor can be made smaller, and the dynamic response of the rectifier is faster. Three-phase PFC technology is still a research hotspot at home and abroad in recent years.

The research on the three-phase high power factor rectification technology mainly focuses on the PWM control mode and topological structure. At present, there have been a lot of researches based on different topological structures. Chinese magazine "Proceedings of the Chinese Society for Electrical Engineering" 2012 Issue 06 " High Power Factor Three-phase Single Transistor Boost PFC Converter" and "Electrical Technology and Electric Energy New Technology" 2003 Issue 02 "Research on Dual-Switch Three-phase Four-Wire PFC Circuit 》A single-switch and double-switch topology is proposed, the number of switches is small, and the control is simple. However, due to the large switching stress of the switching devices, and the circuit works in DCM (discontinuous current mode) mode, the THD is still low. bigger. "A Universal Vector Controller for Four-Quadrant Three-Phase Power Converters" adopts a six-switch topology based on digital DSP control, and uses six switch tubes. The number of switches is large, the conduction loss is large, and the control algorithm is relatively complicated. accomplish.

Contents of the invention

1. Technical problems to be solved

Aiming at the shortcomings in the prior art that the control effect is poor when the control is relatively simple and the control is complicated and difficult to realize when the effect is good, the present invention provides a control circuit for a three-phase high power factor rectifier, which can realize three-phase high power factor rectifier Power factor rectification can obtain a higher-precision steady-state output voltage, has strong anti-interference ability, and is easy to implement.

2. Technical solution

The object of the present invention is achieved through the following technical solutions:

A control circuit for a three-phase high power factor rectifier, including an input high-frequency filter circuit, a three-phase input inductor, and a three-phase rectifier circuit, and also includes a switch tube power circuit, an output rectifier filter circuit, a voltage division detection circuit, and an input current detection unit , single-cycle controller and switching tube drive circuit;

The input high-frequency filter circuit includes three high-frequency filter capacitors C _a , C _b and C _c with the same parameters. One end of C _a , C _b and C _c is respectively connected to the grid A phase voltage input terminal and the grid B The phase voltage input terminal and the C-phase voltage input terminal of the grid, the other end is connected to the neutral wire of the three-phase four-wire power at the same time, and the neutral wire is grounded;

The three-phase input inductance includes three high-frequency BOOST inductances L _a , L _b and L _c with the same parameters;

The three-phase rectifier circuit includes three bridge arms, namely an A-phase bridge arm, a B-phase bridge arm and a C-phase bridge arm;

The switch tube power circuit includes three bidirectional switch tubes S _a , S _b and S _c ; the input voltage of phase A of the power grid is connected to the middle point A of the bridge arm of phase A _and one end of the bidirectional switch tube S a through the inductance L _a , and the power grid The B-phase input voltage is connected to the middle point B of the B-phase bridge arm and one end of _the bidirectional switch S b through the inductor L _b , and the C _- phase input voltage of the power grid is connected to the C-phase bridge arm midpoint C and the bidirectional switch S c through the inductor L _c one end; the other end of the bidirectional switch S _a , S _b and S _c is simultaneously connected to the grid neutral line and driven by the switch tube drive circuit;

The three-phase rectification circuit, the output rectification filter circuit and the voltage division detection circuit are sequentially connected; the single-cycle controller is respectively connected with the voltage division detection circuit, the input current detection unit and the switching tube drive circuit; the input The current detection unit respectively detects the currents flowing through the inductors L _a , L _b and L _c .

Preferably, each of the bidirectional switches S _a , S _b and S _c is composed of four rectifier diodes D _i1 , D _i2 , D _i3 , D _i4 and one IGBT tube K _i , and the cathode of D _i2 is connected to D The anode of _i1 is connected, _the cathode of D _i1 is connected to one end of the inductor in the i-phase circuit, the cathode of D _i4 is connected to the anode of D i3, the cathode of D _i3 is connected to the neutral line, the cathode of D _i1 , the cathode of D _i3 are connected to the collector of the IGBT Together, the anode of D _i2 , the anode of D _i4 and the emitter of the IGBT are connected together, where i=a, b, c, the gate of the IGBT tube is connected with the switch tube drive circuit.

Preferably, the three-phase rectification circuit includes six fast recovery diodes D _ap , D _bp , D _cp , D _an , D _bn and D _cn , the anode of D _ap is connected with the cathode of D _an to form the A-phase bridge arm, The anode of D _bp is connected with the cathode of D _bn to form a B-phase bridge arm, the anode of D _cp is connected to the cathode of D _cn to form a C-phase bridge arm, the cathodes of D _ap , D _bp , and D _cp are connected together, and D _an , The anodes of D _bn and D _cn are connected together.

Preferably, the output rectifying and filtering circuit includes two output electrolytic capacitors _Cp and _Cn , the negative pole of the output electrolytic capacitor _Cp is connected to the positive pole of the output electrolytic capacitor _Cn , and the connection point is connected to the neutral line, The positive pole of the output electrolytic capacitor C _p is connected to the cathodes of D _ap , D _bp and D _cp , and the negative pole of the output electrolytic capacitor C _n is connected to the anodes of D _an , D _bn and D _cn .

Preferably, the divided voltage detection circuit includes output voltage sampling resistors R _FB1 and R _FB2 , output undervoltage sampling resistors R _BOP1 and R _BOP2 and output overvoltage sampling resistors R _OVP1 and R _OVP2 , and each set of voltage sampling resistors is connected in series Afterwards, it is connected in parallel at both ends of the output capacitor _Cp , and lead wires are connected to the single-cycle controller respectively from the connections where each set of voltage sampling resistors are connected in series.

Preferably, the single-cycle controller includes three single-cycle single-phase PFC control chips IR1153S, the sampled value V _FB of the output voltage U _o is respectively connected to the VFB pins of the three chips IR1153S, and is connected to the internal reference voltage V _REF of the chip. The difference after comparison is obtained by the PI modulator to obtain V _m (generated by the pin COMP), and the COMP pins of the three chips are connected to one point in parallel, and then share an external circuit to form a voltage error amplification link to ensure the voltage error of each phase The amplification value V _m is the same, so as to achieve the ideal control effect. The output overvoltage sampling voltage V _OVP is respectively connected to the OVP ports of the three chips. When the voltage is greater than the given voltage value in the chip, the three output duty cycle signals are all zero. , to play the role of overvoltage protection, the output undervoltage sampling voltage V _BOP is respectively connected to the BOP ports of the three chips. Function; the switch tube drive circuit is composed of M57959L chip and its peripheral circuits.

Preferably, the input current detection unit includes three input current sampling circuits, and each input current sampling circuit is composed of a current sensor and a current signal absolute value amplification circuit sequentially connected; the input terminals of the three current sensors are respectively sampled Three channels of inductance current values, the output signal of the inductance current sampling is connected to the single-cycle controller through the output terminal of the absolute value amplifier circuit.

Invention principle: based on the control circuit of the three-phase high power factor rectifier of the present invention, if S _a is turned on when the A-phase input voltage is in the positive half cycle, then the forward current of L _a continues to increase, and when S _a is turned off, the rectifier bridge The upper bridge arm diode D _ap is turned on, L _a charges the capacitor C _p and also supplies power to the load, and the forward current of L _a keeps decreasing; on the contrary, if S _a is turned on when the input voltage of phase A is in the negative half cycle, then L _{a The} reverse current keeps increasing, when the switch tube S _a is turned off, the diode D _an of the lower bridge arm of the rectifier bridge is turned on, L _a charges the capacitor C _n and also supplies power to the load, and the reverse current of L _a keeps decreasing; When S _a is turned on, the voltage across the inductor L _a is the grid voltage U _a ; when S _a is turned off, if U _a is in the positive half cycle, the voltage across the inductor L _a is U _{a -UP} ( _UP is C _p Voltage at both ends), if the grid voltage is in the negative half cycle, the voltage at both ends of the inductor L _a is U _a -U _N (U _N is the voltage at both ends of C _n ); from the volt-second balance, U _a = (1-D _a ) U _P (U _a >0), -U _a = (1-D _a ) U _N (U _a <0), when the circuit reaches a steady state, the voltages on the two capacitors are balanced and half of the output voltage U _o , That is, U _P =U _N =0.5U _o ; therefore, |U _a |=0.5(1-D _a )U _o (D _a is the duty cycle in one switching cycle, the positive pole of C _p and the negative pole of C _n form The voltage is the output voltage U _o );

The output voltage sampling value V _FB of the output voltage U _o is connected to the VFB pin of the chip IR1153S, and the difference after comparing with the internal reference voltage V _REF of the chip is obtained by the PI modulator to obtain V _m (generated by the pin COMP); during the switching cycle At the beginning, S _a is turned on, the voltage at both ends of the inductor L _a is the grid voltage U _a , the current sensor samples the input current signal, and after obtaining the alternating voltage signal, the positive voltage signal is obtained after the absolute value amplification circuit and connected to the control chip IR1153S The current sampling signal input terminal forms a current loop; at this time, after the inductance current passes through the absolute value amplification circuit, its output value continues to increase, while the output of the integrator continues to decrease. When the current sampling value is greater than the output of the integrator, S _a is turned off. At the end of the switching cycle, reset the integrator, and repeat this process to obtain the required duty ratio signal; therefore, the sampling current of each phase in each cycle and its switch-on duty ratio satisfy: V _m (1-D _a )=V _ia ; combined with the relationship between the sampling current and its switch-on duty cycle, it can be obtained: U _a = U _o V _ia /2V _m , in steady state, U _o and V _m are constant values, V _ia = ki _a and k is a constant , record R _e =kU _o /2V _m , then U _a =R _e i _a ; thus the output load of phase A can be equivalent to a pure resistance load, so that the input current waveform follows its phase voltage into a sinusoidal change, and the phase angle is Zero, achieving unity power factor;

The working principle of phase B, phase C and phase A is the same, so for three-phase input, each single-phase output load can be equivalent to a pure resistance load, and the size is equal;

The COMP pins of the three IR1153S chips are connected in parallel and share an external PI regulator circuit (composed of C _Z , C _P , R _gm ) to obtain the same output voltage error amplification signal V _m , and the output overvoltage sampling voltage V _OVP is simultaneously connected to The corresponding pins of the three single-cycle control chips, when the voltage is greater than the given voltage value in the chip, the output duty cycle signal is zero, and the output voltage decreases; the output undervoltage sampling voltage V _BOP is connected to the corresponding pins of the three single-cycle control chips at the same time Pin, before the voltage value is lower than the chip setting value, the duty cycle signal is blocked.

3. Beneficial effect

Compared with the prior art, the present invention has the advantages of:

(1) The present invention adopts a single-cycle control strategy, the control method is simple, the required detection amount is less, and only the input current and output voltage need to be sampled, which improves the stability of the system to a certain extent;

(2) The present invention adopts the topology structure of three-phase four-wire system, and theoretically analyzes and realizes the decoupling between the three phases. After decoupling, the three phases are independent of each other, and the circuit can still work normally when the grid voltage fluctuates or lacks a phase. , the system has strong anti-interference ability, and under this topology, the voltage that the switching tube bears is half of the output voltage, the switching stress is small, and there is no danger of straight-through of the rectifier bridge arm when the current commutates;

(3) The present invention uses a mature single-phase single-cycle control chip to control the corresponding phases respectively, so that the phase current follows its voltage into a sinusoidal change, thus greatly reducing the product development cycle, and the peripheral wiring of the chip is simple, and the obtained three-phase The rectifier has high input power factor, high stability, strong anti-interference ability, and has wide application value.

Description of drawings

Fig. 1 is a schematic block diagram of the present invention;

Fig. 2 is the current sampling absolute value amplification circuit diagram;

Figure 3 is the peripheral wiring diagram of three single-cycle control chips IR1153S;

Fig. 4 is a bidirectional switch circuit diagram;

Figure 5 is a schematic diagram of single-cycle control.

In the figure: 1. Input high-frequency filter circuit; 2. Three-phase input inductance; 3. Three-phase rectification circuit; 4. Switch tube power circuit; 5. Output rectification filter circuit; 6. Voltage division detection circuit; 7. Input current Detection unit; 8. Single-cycle controller; 9. Switch tube drive circuit.

Detailed ways

The present invention will be described in detail below in conjunction with the accompanying drawings and specific embodiments.

Example

The control circuit of the three-phase high power factor rectifier of this embodiment, as shown in Figure 1, it includes input high-frequency filter circuit 1, three-phase input inductor 2, three-phase rectification circuit 3, switch tube power circuit 4, output rectification filter A circuit 5 , a voltage division detection circuit 6 , an input current detection unit 7 , a single-cycle controller 8 and a switching tube drive circuit 9 .

The input high-frequency filter circuit 1 includes three ceramic capacitors C _a , C _b and C _c with a withstand voltage of 630V and a size of 2.2uF. One end of C a , C _{b and} C _c is respectively connected to the grid A-phase voltage input terminal, grid B-phase voltage input terminal and grid C-phase voltage input terminal, and the other end is simultaneously connected to the neutral wire of the three-phase four-wire power, and the neutral wire is grounded. The three-phase input inductor 2 includes three high-frequency BOOST inductors L _a , L _b and L _c with an inductance value of 400 uH. The three-phase rectification circuit 3 includes six fast recovery diodes D _ap , D _bp , D _cp , D _bn , D _an and D _cn of the model G80N60. The anode of D _ap is connected to the cathode of D _an to form the A-phase bridge arm, which is connected to The point is A, the anode of D _bp is connected to the cathode of D _bn to form a B-phase bridge arm, the connection point is B, the anode of D _cp is connected to the cathode of D _cn to form a C-phase bridge arm, and the connection point is C. The cathodes of D _ap , D _bp , and D _cp are connected together, while the anodes of D _an , D _bn , and D _cn are connected together.

The switching tube power circuit 4 includes three bidirectional switching tubes S _a , S _b and S _c . As shown in Figure 4, each bidirectional switch tube consists of a rectifier bridge KPBC3510 connected in parallel with an IGBT tube K _i of model K75T60 (i=a, b, c). One end of the bidirectional switch tube is connected to the midpoint of the corresponding bridge arm, and the other One end is connected to the grid neutral wire. The three-phase rectification circuit 3, the output rectification filter circuit 5 and the voltage division detection circuit 6 are sequentially connected, and the single-cycle controller 8 is respectively connected with the voltage division detection circuit 6, the input current detection unit 7 and the switch tube drive circuit 9, and the described The input current detection unit 7 respectively detects the currents flowing through the inductors L _a , L _b and L _c .

The output rectification filter circuit 5 includes two electrolytic capacitors C _p and C _n with a capacity value of 1000uH and a withstand voltage of 630V. The negative pole of C _p is connected to the positive pole of C _n , the connection point is grounded, and the positive pole of C _p is connected to D _ap The cathode of C _n is connected to the anode of _Dan . The voltage formed by the positive pole of C _p and the negative pole of C _n at both ends of the two output capacitors is the output voltage U _o of the rectifier, and the load R _o is connected in parallel to the output end of the rectifier.

As shown in Figure 2 and Figure 3, the single-cycle controller 8 includes three single-cycle single-phase PFC control chips IR1153S, the power supply of the three single-phase PFC control chips is 15V, the three chips use one power supply, and the ground signal COM The pin is connected to the neutral line of the grid. The output voltage sampling voltage V _FB is respectively connected to the VFB pins of the three chips as the voltage outer ring to obtain a stable voltage output. The difference between the sampled value V _FB of the output voltage U _o and the internal reference voltage V _REF of the chip is obtained by the PI regulator to obtain V _m (generated by the pin COMP), and the COMP pins of the three chips are connected in parallel to one point, and then share a An external circuit forms a voltage error amplification link to ensure that the voltage error amplification value V _m of each phase is the same, so as to achieve the ideal control effect. The output overvoltage sampling voltage V _OVP is respectively connected to the OVP ports of the three chips. When the voltage is greater than Given the voltage value in the chip, the output duty cycle signal is zero, and the output voltage decreases, which plays the role of overvoltage protection. Connect the output undervoltage sampling voltage V _BOP to the BOP ports of the three chips respectively. Before the voltage value is lower than the chip setting value, the duty cycle signal is blocked to protect the undervoltage to a certain extent and play a soft role when the rectifier starts. Start the effect. The three-phase current sampling signals are respectively connected to the ISNS pin of the chip through the resistor R _SFM (M=1, 2, 3), where R _SFM is 100 ohms, C _SFN (N=1, 2, 3) is 100nF, and C _Z , C _S , and R _gm are external PI adjustment parameters of the chip. In order to obtain the same PI adjustment output, the three chips use the same external capacitor resistance circuit, and select C _Z =0.47uF, C _S =10nF, R _gm =4.7K , in order to obtain better dynamic response results, the size of each parameter can be appropriately changed, and finally the PWM signal generated by the chip is amplified by the IGBT driver chip M57959L to drive the respective IGBT tubes. The switching tube drive circuit 9 is composed of M57959L chip and its peripheral circuits.

The current detection unit 7 includes three input current sampling circuits, and each input current sampling circuit is composed of a current sensor and a current signal absolute value amplification circuit sequentially connected. Three current sensors sample the input current i _j (j=a, b, c), and the sensor conversion coefficient is 0.1, that is, u _j =0.1i _j (j=a, b, c, u _j is the output voltage value of the current sensor) . After the alternating voltage signal is obtained, the appropriate negative voltage signal is obtained through the absolute value amplification circuit shown in Figure 2 and connected to the corresponding input terminal of the current sampling signal of the control chip IR1153S to form a current loop. The corresponding duty cycle signal is obtained in each cycle, and then the turn-on time of the IGBT tube is controlled after driving the amplifying circuit, so that the phase current reaches a predetermined value. Finally, the control makes the input current follow the input voltage to change sinusoidally, and the phase angle is zero, so the three-phase high power factor rectification effect is realized.

U _a , U _b , U _c are three-phase input voltages, whose effective value is 240V, U _o is the output voltage, whose value is 750V, and the output power of the converter is 6KW. By changing the turn-on and turn-off of the switch tube, when the input voltage of phase A, B or C is in the positive half cycle, the switch tube is turned on, and the inductor current increases continuously in the positive direction. When the switching tube is turned off, the upper bridge arm diode D _ip (i=a, b, c) of the corresponding phase rectifier bridge is turned on, charging the electrolytic capacitor C _p while also supplying power to the load, and the inductor current is continuously decreasing in the positive direction . On the contrary, when the input voltage of phase A, B or C is in the negative half cycle, the switch tube is turned on, and the inductor current increases continuously in the opposite direction, and when the switch tube is turned off, the lower bridge arm diode D _in of the corresponding phase rectifier bridge (i= a, b, c) are turned on, charging the capacitor C _n and supplying power to the load at the same time.

In order to reduce the power consumption of the entire voltage divider resistor and have enough input bias current to ensure the output of the error amplifier, the voltage divider detection circuit 6 is selected as a compromise to output the voltage sampling resistor R _FB1 =2M ohms. The size of R _FB2 can be calculated according to the required output voltage U _o , and its calculation formula is:

${\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="R\; Facebook"\; filenames="130411142030.png,130411142039.png"\; state="\{\{state\}\}">R</figure-callout></span><figure-callout\; id="2"\; label="R\; Facebook"\; filenames="130411142030.png,130411142039.png"\; state="\{\{state\}\}">\; </figure-callout>}}_{\mathrm{<span\; class="notranslate">\; </span>}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; REF</span>}}{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; Facebook</span>}\mathrm{<span\; class="notranslate">\; 1</span>}}}{<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; 0.5</span>}\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; o</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; REF</span>}}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>$

Among them, V _REF is the reference voltage generated inside the chip, its value is 5V, and the calculated R _FB2 is 27K ohms. The output undervoltage sampling resistor is R _BOP1 = 4.8M ohms, and two 2.4M ohm resistors are connected in series. R _BOP2 is determined by the following formula:

${\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="R\; BOP"\; filenames="130411142030.png,130411142039.png"\; state="\{\{state\}\}">R</figure-callout></span><figure-callout\; id="2"\; label="R\; BOP"\; filenames="130411142030.png,130411142039.png"\; state="\{\{state\}\}">\; </figure-callout>}}_{\mathrm{<span\; class="notranslate">\; </span>}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; BOP</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; HI</span>}<span\; class="notranslate">\; )</span>}{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; BOP</span>}\mathrm{<span\; class="notranslate">\; 1</span>}}}{<span\; class="notranslate">\; (</span>\sqrt{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; AC</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; ON</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; BOP</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; HI</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; BRIDGE</span>}}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; )</span>$

Among them, V _{BOP (HI)} is the reference voltage generated inside the chip, its value is 1.56V, V _BRIDGE is 2V, V _{AC, ON} is the effective value of the input voltage, and R _BOP2 can choose a resistor with a resistance value of 35K ohms. Select the output overvoltage feedback resistor R _OVP1 = 2M ohms, and R _OVP2 is determined by the following formula:

${\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="R\; OVP"\; filenames="130411142030.png,130411142039.png"\; state="\{\{state\}\}">R</figure-callout></span><figure-callout\; id="2"\; label="R\; OVP"\; filenames="130411142030.png,130411142039.png"\; state="\{\{state\}\}">\; </figure-callout>}}_{\mathrm{<span\; class="notranslate">\; </span>}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; OVP</span>}}{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; OVP</span>}\mathrm{<span\; class="notranslate">\; 1</span>}}}{<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; 0.5</span>}\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; o</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; OVP</span>}}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 3</span>}<span\; class="notranslate">\; )</span>$

Generally take the overvoltage V _OVP =1.06V _REF , so the calculated resistance R _OVP2 =29K ohms.

Various voltage sampling resistors are connected in series and then connected in parallel at both ends of the electrolytic capacitor C _p of the upper bridge arm, and wires are drawn from the respective connections to the single-cycle control chip IR1153S.

The current sensor samples the current signal at the input terminal to obtain the output voltage signal as u _j (j=a, b, c), and obtains U _oj (j=a, b, c) through the absolute value circuit A ₁ and A ₂ , where U _oj = |u _j |, in the circuit, the resistance value of R ₁ is 3K ohms, the resistance value of R ₂ , R ₃ , R ₄ , R ₅ , and R ₇ is usually 10K ohms, D ₁ D ₂ is the diode IN4148, and then the operational amplifier A ₃ amplifies U _oj (the magnification factor is determined by resistors R ₇ and R ₈ ), and obtains V _ij =-(R ₈ /R ₇ ) U _oj (j=a, b, c), R ₇ and R ₈ The resistance value should be selected according to the size of the output signal of the current sensor when the input current reaches the maximum value in the circuit design, and the limit of the input voltage amplitude of the control chip to determine the selection of parameters. V _ij (j=a, b, c) must be in ( -0.68V～0V), in order to meet this requirement, take R ₈ /R ₇ =1/3 in this design.

The principle of single-cycle control adopted by the present invention is to control the duty cycle of the switch in real time, so that the control quantity reaches the reference signal value in each switching cycle, and finally can realize unity power factor and low current distortion.

To simplify the analysis, the A-phase circuit is taken as an example. When S _a is turned on, the voltage across the inductor L _a is the grid voltage U _a . When S _a is turned off, if the grid voltage is in the positive half cycle, the voltage across the inductor L _a is U _a -UP; if the grid voltage is in the negative half cycle, the voltage across the inductor L _a is U _a -U _N . From the volt-second balance we get:

U _a =(1-D _a )U _p (U _a >0) (4)

-U _a =(1-D _a )U _N (U _a <0) (5)

D _a is the duty cycle in one switching cycle. When the circuit reaches a steady state, the voltages on the two capacitors are balanced and half of the output voltage, that is, U _P =U _N =0.5U _o , therefore:

|U _a |=0.5(1-D _a )U _o (6)

As shown in Figure 3, the difference between the sampled value V _FB of the output voltage U _o and the internal reference voltage V _REF of the chip is obtained by the PI modulator to obtain V _m (generated by the pin COMP), and the clock cycle of the chip is 22KH _Z , analyzed in conjunction with Fig. 5, at the beginning of each switching cycle, the internal RS flip-flop is set by the internal clock signal Clock1, and the power switch is turned on. The current sampling signal is connected to the respective comparator input terminals, and the other input terminal of the comparator is connected to the output of the reset integrator. The integration time is the same as the switching period, and the output voltage value of the reset integrator is V _m (1-D _a ). When the current sampling value reaches the output voltage value of the reset integrator, its corresponding trigger will be reset, and the corresponding switch tube will be turned off. Before the end of a cycle, the clock2 signal will clear the integrator to prepare for the next cycle. And the switch duty cycle can be obtained:

D _a =1-V _ia /V _m (7)

Put formula (7) into formula (6) to get:

U _a =U _o V _ia /2V _m (8)

In the steady state, U _o and V _m are constant values, V _ia =ki _a , where k is the current sampling coefficient, and k is a constant after the current sampling parameter is selected, write R _e =kU _o /2V _m , it can be obtained:

U _a =R _e .i _a (9)

The same is true for the other two phases, so for three-phase input, each single-phase output load can be equivalent to a pure resistance load, and the magnitude is equal, namely:

U _a =R _e ×i _a , U _b =R _e ×i _b ,U _c =R _e ×i _c (10)

The above formula shows that this control scheme can make the input impedance of each phase of the converter to be pure impedance, so that the input current waveform of each phase changes sinusoidally following its phase voltage, the phase angle is zero, and the unity power factor is realized.

The above schematically describes the present invention and its implementation, which is not restrictive, and what is shown in the drawings is only one of the implementations of the present invention, and the actual structure is not limited thereto. Therefore, if a person of ordinary skill in the art is inspired by it, without departing from the purpose of the invention, without creatively designing a structure and an embodiment similar to the technical solution, it shall fall within the scope of protection of this patent.

Claims (7)

1. the control circuit of a three-phase high power factor rectifier, comprise input high-frequency filter circuit (1), three-phase input inductance (2) and rectified three-phase circuit (3), it is characterized in that, also comprise switching tube power circuit (4), output rectifier and filter (5), voltage-dividing detection circuit (6), input current detecting unit (7), single cycle controller (8) and switching tube drive circuit (9);

Described input high-frequency filter circuit (1) comprises three high-frequency filter capacitor C that parameter is identical _a, C _bAnd C _c, C _a, C _bAnd C _cAn end respectively correspondence be connected to electrical network A phase voltage input, electrical network B phase voltage input and electrical network C phase voltage input, the other end is connected to the neutral line of three-phase and four-line electricity, neutral earthing simultaneously;

Described three-phase input inductance (2) comprises three high frequency BOOST inductance L that parameter is identical _a, L _bAnd L _c

Described rectified three-phase circuit (3) comprises three brachium pontis, i.e. A phase brachium pontis, B phase brachium pontis and C brachium pontis mutually;

Described switching tube power circuit (4) comprises three bidirectional switch pipe S _a, S _bAnd S _cElectrical network A phase input voltage is through inductance L _aBe connected to A phase brachium pontis mid point A and bidirectional switch pipe S _aAn end, electrical network B phase input voltage is through inductance L _bBe connected to B phase brachium pontis mid point B and bidirectional switch pipe S _bAn end, electrical network C phase input voltage is through inductance L _cBe connected to C phase brachium pontis mid point C and bidirectional switch pipe S _cAn end; Described bidirectional switch pipe S _a, S _bAnd S _cThe other end insert network neutral line simultaneously and driven by switching tube drive circuit (9);

Described rectified three-phase circuit (3), output rectifier and filter (5) and voltage-dividing detection circuit (6) are connected successively; Described single cycle controller (8) is connected with voltage-dividing detection circuit (6), input current detecting unit (7) and switching tube drive circuit (9) respectively; Described input current detecting unit (7) detects the inductance L of flowing through respectively _a, L _bAnd L _cAfter electric current.

2. the control circuit of a kind of three-phase high power factor rectifier according to claim 1 is characterized in that, described bidirectional switch pipe S _a, S _bAnd S _cEach is by four rectifier diode D _I1, D _I2, D _I3, D _I4With an IGBT pipe K _iForm D _I2Negative electrode and D _I1Anode links to each other, D _I1Negative electrode be connected to inductance one end in the i circuitry phase, D _I4Negative electrode and D _I3Anode links to each other, D _I3Negative electrode be connected to center line, D _I1Negative electrode, D _I3Negative electrode and the collector electrode of IGBT link together D _I2Anode, D _I4Anode and the emitter of IGBT link together, wherein, i=a, b, c, the grid of IGBT pipe is connected with switching tube drive circuit (9).

3. the control circuit of a kind of three-phase high power factor rectifier according to claim 1 is characterized in that, described rectified three-phase circuit (3) comprises six fast recovery diode D _Ap, D _Bp, D _Cp, D _An, D _BnAnd D _Cn, D _ApAnode and D _AnNegative electrode be connected to form A phase brachium pontis, D _BpAnode and D _BnNegative electrode be connected to form B phase brachium pontis, D _CpAnode and D _CnNegative electrode be connected to form C phase brachium pontis, D _Ap, D _Bp, D _CpNegative electrode link together D simultaneously _An, D _BnAnd D _CnAnode link together.

4. according to the control circuit of claim 1 or 2 or 3 described a kind of three-phase high power factor rectifiers, it is characterized in that described output rectifier and filter (5) comprises two output electrochemical capacitor C _p, C _n, described output electrochemical capacitor C _pNegative pole and described output electrochemical capacitor C _nPositive pole link to each other, tie point connects to neutral, described output electrochemical capacitor C _pPositive pole connect D _Ap, D _BpAnd D _CpNegative electrode, described output electrochemical capacitor C _nNegative pole connect D _An, D _BnAnd D _CnAnode.

5. the control circuit of a kind of three-phase high power factor rectifier according to claim 4 is characterized in that, described voltage-dividing detection circuit (6) comprises output voltage sampling resistor R _FB1, R _FB2, output under voltage sampling resistor R _BOP1, R _BOP2With output over-voltage sampling resistor R _OVP1, R _OVP2, each is organized and is connected in parallel on output capacitance C after voltage sample resistance is in series _pTwo ends, and draw lead from the junction of each group voltage sample resistance series connection and insert described single cycle controller (8) respectively.

6. the control circuit of a kind of three-phase high power factor rectifier according to claim 5 is characterized in that, described single cycle controller (8) comprises three monocycle Single-phase PFC control chip IR1153S, output voltage U _oSampling value V _FBBe connected to the VFB pin of three chip I R1153S respectively, the COMP pin of three chips is parallel to a bit, shares an external circuits again, constitutes a voltage error amplifying element, output over-voltage sampled voltage V _OVPReceive the OVP mouth of three chips respectively, output under voltage sampled voltage V _BOPReceive the BOP mouth of three chips respectively; Described switching tube drive circuit (9) is made of M57959L chip and peripheral circuit thereof.

7. the control circuit of a kind of three-phase high power factor rectifier according to claim 6, it is characterized in that, described input current detecting unit (7) comprises three input current sample circuits, and each input current sample circuit is connected and composed successively by current sensor and current signal absolute value amplifying circuit; The input of described three current sensors three road inductive current values of sampling respectively, the output signal of described inductive current sampling is connected with single cycle controller (8) through the output of absolute value amplifying circuit.

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