阅读说明：本技术 一种高压直流电源控制系统及其控制方法 (High-voltage direct-current power supply control system and control method thereof ) 是由 曹何金生 王尉舟 吴淞 罗天生 于 2019-09-11 设计创作，主要内容包括：本发明公开了一种高压直流电源控制系统及其控制方法。通过采样母线电压反馈至DC/DC电路来实现输出电压的调节,逆变器工作在固定频率且变压器电流为近似纯正弦电流,逆变桥的开关管工作在零电压、零电流的开通、关断状态。本发明的电源控制系统可以得到很好的电容兼容性能,同时母线电压控制的方法也满足于高压电源这种对带宽要求不高的系统中。(The invention discloses a high-voltage direct-current power supply control system and a control method thereof. The output voltage is regulated by feeding back the sampled bus voltage to the DC/DC circuit, the inverter works at a fixed frequency, the transformer current is approximate pure sinusoidal current, and the switching tube of the inverter bridge works in the on-off state of zero voltage and zero current. The power supply control system can obtain good capacitance compatibility, and meanwhile, the bus voltage control method can also meet the requirement of a high-voltage power supply in a system with low bandwidth requirement.)

1. A high-voltage direct-current power supply control system comprises a DC/DC circuit, an inverter, a filter topology, a transformer, a rectifying circuit and a bus voltage regulating module;

the DC/DC circuit, the inverter, the filter topology, the transformer and the rectifying circuit are sequentially connected in a circuit mode, voltage Uin is input and output by the DC/DC circuit, and high-voltage direct current Uo is output by the rectifying circuit;

the bus voltage regulating module comprises a sampling circuit, a first-stage PI compensation network and a second-stage PI compensation network;

the input end of the sampling circuit is connected with the output end of the rectifying circuit in a circuit mode, the sampling circuit, the first-stage PI compensation network and the second-stage PI compensation network are sequentially connected in a circuit mode, the output end of the second-stage PI compensation network is connected with the DC/DC input end, and the output end of the DC/DC is connected to the second-stage PI compensation network in a feedback mode; the method comprises the steps of comparing output voltage fed back by a sampling circuit with a preset output voltage reference value to obtain a first comparison signal, inputting the first comparison signal into a first-stage PI compensation network, outputting the first compensation signal by the first-stage PI compensation network, comparing the first compensation signal with a feedback signal output by a DC/DC circuit to obtain a second comparison signal, inputting the second comparison signal into a second-stage PI compensation network, outputting the second compensation signal by the second-stage PI compensation network, and outputting the second compensation signal to the DC/DC circuit.

2. The HVDC power supply control system of claim 1, wherein the topology of the DC/DC circuit is buck, boost or flyback topology.

3. The hvdc power control system of claims 1-2, wherein the inverter is in a half bridge or full bridge topology.

4. The HVDC power supply control system of claims 1-3, wherein the switching tubes of the inverter are MOSFET or IGBT semiconductor switching devices.

5. The HVDC power supply control system of claims 1-4, wherein the filter topology is an LC network, an LC series, an LCC structure, an LLC structure, or only one DC blocking capacitor.

6. A control method of a high-voltage direct-current power supply comprises the steps of comparing an output voltage fed back by a sampling circuit with a preset output voltage reference value to obtain a first comparison signal, inputting the first comparison signal into a first-stage PI compensation network, outputting the first compensation signal by the first-stage PI compensation network, comparing the first compensation signal with a feedback signal output by a DC/DC circuit to obtain a second comparison signal, inputting the second comparison signal into a second-stage PI compensation network, outputting the second compensation signal by the second-stage PI compensation network, and outputting the second compensation signal to the DC/DC circuit by the second-stage PI compensation network according to the control system of the high-voltage direct-current power supply in claims 1-6.

7. The method of claim 6, wherein the operating frequency of the inverter is a fixed frequency that is near the resonant frequency of the filter topology and the transformer.

8. The method for controlling the HVDC power supply of claim 7, wherein the output voltage waveform of the inverter is square wave and the current of the transformer is approximately pure sinusoidal current.

9. The control method of the high-voltage direct-current power supply according to claim 7, wherein the switching tube of the inverter is controlled by soft switching, that is, the switching tube works in a zero-voltage zero-current on or off state.

10. The control method of the high-voltage direct current power supply according to claim 9, wherein the soft switching control is specifically that the frequency of the inverter is near the resonant frequency, the current and voltage phases at the resonant frequency point are the same, the frequency is near the resonant frequency, and the current phase is slightly behind the voltage phase; at the time 0-t0, the current is positive, the upper tube is on, at the time t0, the voltage drop of the upper tube is about 0, the current is about 0, and at the time t0, the upper tube is off, which meets the requirements of zero voltage and zero current off; at the time t0-t2, the current is about 0, the tube diode is in follow current, the voltage drop is the diode voltage drop which is about 0, the current is about 0, the tube is switched on at the time t2, and the zero voltage and zero current switching is met; at the time of t2-t3, the lower tube is switched on, the current is negative, at the time of t3, the voltage drop of the lower tube is about 0, the current is about 0, and the lower tube is switched off at the time of t3, so that zero voltage and zero current switching are met; at time t3-t5, the current is about 0 and the tube diode freewheels, the voltage drops to a diode drop of about 0 and the current is about 0, and at time t5 the tube turns on, which satisfies zero voltage and zero current turn on.

11. The method for controlling the high-voltage direct current power supply according to claim 6, wherein the DC/DC is a boost topology structure, and a constant on-time control method, a constant off-time control method, a V2 control method, a peak current control method or a valley current method is adopted.

Technical Field

The invention belongs to the technical field of high-voltage direct-current power supplies, and particularly relates to a high-voltage direct-current power supply control system and a control method thereof.

Background

The traditional control mode of the high-voltage direct-current power supply mainly adopts a frequency conversion voltage regulation control mode and a PWM control mode. For example, the high-voltage power supply of the LCC topology structure mostly adopts a frequency conversion method to change the energy transmitted in a unit period, thereby changing the output voltage; the flyback topology structure and the self-excited topology structure mostly adopt a PWM method, and the energy transmitted in a unit period is changed by changing the duty ratio, so that the output voltage is changed. Further, there are a charge control method, a single cycle control method, and the like. The methods achieve the purpose of changing the regulation output by changing the driving behavior of the inverter bridge; and the bus voltage is considered to be a source of interference or a fixed amount. The above control method has certain advantages in the case of requiring bandwidth requirements. The high-voltage direct-current power supply has a large time constant and a small bandwidth due to a large filtering link and a voltage-multiplying rectifying circuit on the secondary side. Meanwhile, most application scenes of the high-voltage direct-current power supply have low requirements on bandwidth, and the requirements on ripple waves are higher.

No matter in a frequency conversion control mode or a PWM control mode, the transformer current of the high-voltage direct-current power supply is not pure sinusoidal, zero current turn-off, zero current turn-on, zero voltage turn-on and zero voltage turn-off cannot be realized, and the problem of electromagnetic interference is also a great challenge. No matter the limitation of the control mode or the consideration of the problem of switching loss, the working frequency of the transformer cannot reach hundreds of kHz, and the further use efficiency of the transformer is limited. And the design burden of the output filter is increased.

Disclosure of Invention

Aiming at the defects or the improvement requirements of the prior art, the invention provides a high-voltage direct-current power supply control system and a control method, the output voltage regulation is realized by bus voltage regulation, an inverter works at a fixed frequency, the current of a transformer is approximate pure sine current, and a switching tube of an inverter bridge works at the on-off state of zero voltage and zero current. The power supply control system can obtain good capacitance compatibility, and meanwhile, the bus voltage control method can also meet the requirement of a high-voltage power supply in a system with low bandwidth requirement.

In order to achieve the aim, the invention provides a high-voltage direct-current power supply control system which comprises a DC/DC circuit, an inverter, a filter topology, a transformer, a rectifying circuit and a bus voltage regulating module;

the DC/DC circuit, the inverter, the filter topology, the transformer and the rectifying circuit are sequentially connected in a circuit mode, voltage Uin is input through the DC/DC circuit, and high-voltage direct current Uo is output through the rectifying circuit;

the bus voltage regulating module comprises a sampling circuit, a first-stage PI compensation network and a second-stage PI compensation network;

the input end of the sampling circuit is connected with the output end of the rectifying circuit in a circuit mode, the sampling circuit, the first-stage PI compensation network and the second-stage PI compensation network are sequentially connected in a circuit mode, and the output end of the second-stage PI compensation network is connected with the DC/DC input end; the output end of the DC/DC is connected to the second-stage PI compensation network in a feedback mode; the method comprises the steps of comparing output voltage fed back by a sampling circuit with a preset output voltage reference value to obtain a first comparison signal, inputting the first comparison signal into a first-stage PI compensation network, outputting the first compensation signal by the first-stage PI compensation network, comparing the first compensation signal with a feedback signal output by a DC/DC circuit to obtain a second comparison signal, inputting the second comparison signal into a second-stage PI compensation network, outputting the second compensation signal by the second-stage PI compensation network, and outputting the second compensation signal to the DC/DC circuit.

Further, the topology of the DC/DC circuit is buck, boost, flyback, etc., and is preferably a boost topology.

Further, the inverter is in a half-bridge or full-bridge topology.

Further, the switching tube of the inverter is a MOSFET or IGBT semiconductor switching device.

Furthermore, the current of the transformer is an approximate pure sine current waveform, the frequency of the current is close to the resonance frequency of the system, the current phase slightly lags behind the voltage phase, and the lag angle is not limited.

Further, the filtering topology is an LC network, an LC series, an LCC structure, an LLC structure or only one blocking capacitor.

Further, the switching tube works in the on or off state of zero voltage and zero current.

The invention also provides a control method of the high-voltage direct-current power supply, which comprises the steps of comparing the output voltage fed back by the sampling circuit with a preset output voltage reference value to obtain a first comparison signal, inputting the first comparison signal into a first-stage PI compensation network, outputting the first compensation signal by the first-stage PI compensation network, comparing the first compensation signal with the feedback signal output by the DC/DC circuit to obtain a second comparison signal, inputting the second comparison signal into a second-stage PI compensation network, outputting the second compensation signal by the second-stage PI compensation network, and outputting the second compensation signal to the DC/DC circuit.

Further, the operating frequency of the inverter is a fixed frequency, and the fixed frequency is near the resonant frequency of the filter topology and the transformer.

Furthermore, the switching tube of the inverter is controlled by adopting a soft switch, and the soft switch control is specifically that the frequency of the inverter is near the resonant frequency, the current and voltage phases at the resonant frequency point are the same, the frequency is near the resonant frequency, and the current phase slightly follows the voltage phase; at the time 0-t0, the current is positive, the upper tube is on, at the time t0, the voltage drop of the upper tube is about 0, the current is about 0, and at the time t0, the upper tube is off, which meets the requirements of zero voltage and zero current off; at the time t0-t2, the current is about 0, the tube diode is in follow current, the voltage drop is the diode voltage drop which is about 0, the current is about 0, the tube is switched on at the time t2, and the zero voltage and zero current switching is met; at the time of t2-t3, the lower tube is switched on, the current is negative, at the time of t3, the voltage drop of the lower tube is about 0, the current is about 0, and the lower tube is switched off at the time of t3, so that zero voltage and zero current switching are met; at time t3-t5, the current is about 0 and the tube diode freewheels, the voltage drops to a diode drop of about 0 and the current is about 0, and at time t5 the tube turns on, which satisfies zero voltage and zero current turn on.

Further, the output voltage waveform of the inverter is a square wave, and the current of the transformer is an approximately pure sine current.

Further, the DC/DC is a boost topology, and a constant on-time control method, a constant off-time control method, a V2 control method, a peak current control method, or a valley current method is adopted.

Compared with the prior art, the invention has the beneficial effects that: according to the method, the output voltage is regulated by feeding back the voltage of the sampling bus to the DCDC circuit, the inverter works at a fixed frequency, the current of the transformer is approximate pure sinusoidal current, and the switching tube of the inverter bridge works in the on and off states of zero voltage and zero current. The power supply control system can obtain good capacitance compatibility, and meanwhile, the bus voltage control method can also meet the requirement of a high-voltage power supply in a system with low bandwidth requirement.

Drawings

FIG. 1 is a block diagram of a system constructed in accordance with a preferred embodiment of the present invention;

FIG. 2 is a schematic diagram of a control method of the high voltage DC power supply of the present invention;

FIG. 3 is a schematic diagram of a single bridge arm for implementing soft switching control according to the present invention;

FIG. 4 is a driving control waveform of a single bridge arm for implementing soft switching control according to the present invention;

fig. 5 is a detailed composition structural diagram of a preferred embodiment of the high-voltage direct-current power supply control system of the invention.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention. In the embodiments of the present invention, the first, second, etc. are used only for distinguishing different description objects unless otherwise specified.

As shown in fig. 1 and 5, the high voltage direct current power supply control system of the invention comprises a DC/DC circuit, an inverter, a filter topology, a transformer, a rectification circuit and a bus voltage regulation module; the DC/DC circuit, the inverter, the filter topology, the transformer and the rectifying circuit are sequentially connected in a circuit mode, voltage Uin is input through the DC/DC circuit, and high-voltage direct current Uo is output through the rectifying circuit; the bus voltage regulating module comprises a sampling circuit, a first-stage PI compensation network and a second-stage PI compensation network; the input end of the sampling circuit is connected with the output end of the rectifying circuit in a circuit mode, the sampling circuit, the first-stage PI compensation network and the second-stage PI compensation network are sequentially connected in a circuit mode, and the output end of the second-stage PI compensation network is connected with the DC/DC input end; the output end of the DC/DC is connected to the second-stage PI compensation network in a feedback mode; the method comprises the steps of comparing output voltage fed back by a sampling circuit with a preset output voltage reference value to obtain a first comparison signal, inputting the first comparison signal into a first-stage PI compensation network, outputting the first compensation signal by the first-stage PI compensation network, comparing the first compensation signal with a feedback signal output by a DC/DC circuit to obtain a second comparison signal, inputting the second comparison signal into a second-stage PI compensation network, outputting the second compensation signal by the second-stage PI compensation network, and outputting the second compensation signal to the DC/DC circuit.

The topological structure of the DC/DC circuit is buck, boost, flyback and the like, and is preferably a boost topological structure.

The inverter is in a half-bridge or full-bridge topology structure.

And the switching tube of the inverter is an MOSFET or IGBT semiconductor switching device.

The current of the transformer is approximate pure sine current waveform, the frequency of the transformer is near the resonance frequency of the system, the requirement that the current phase slightly lags behind the voltage phase is met, and the lag angle is not limited.

The filtering topology is an LC network, an LC series connection, an LCC structure, an LLC structure or only one blocking capacitor.

The switching tube works in the on or off state of zero voltage and zero current.

As shown in fig. 2 and 5, the control method of the high voltage DC power supply of the present invention includes the above-mentioned high voltage DC power supply control system comparing the output voltage fed back by the sampling circuit with a preset output voltage reference value to obtain a first comparison signal, inputting the first comparison signal into the first stage PI compensation network, the first stage PI compensation network outputting the first compensation signal, comparing the first compensation signal with the feedback signal output by the DC/DC circuit to obtain a second comparison signal, inputting the second comparison signal into the second stage PI compensation network, the second stage PI compensation network outputting the second compensation signal, and outputting the second compensation signal to the DC/DC circuit.

The working frequency of the inverter adopts a control mode of fixed frequency.

The switching tube of the inverter works in a soft switching state, namely the switching tube meets the soft switching characteristics of zero voltage and zero current when being switched on and switched off.

The working current of the transformer is approximately pure sine current.

The DC/DC is a boost topological structure and adopts a constant conduction time control method.

Because the inverter operates at a fixed frequency, which is near the resonant frequency of the LC network and the transformer, and the inverter output voltage waveform is a square wave (duty cycle 50%), the transformer output current waveform is an approximately sinusoidal current, and the voltage transfer characteristics of the inverter + LC network + transformer are:

wherein k is the relationship between the output voltage and the inverter frequency under the unit bus voltage; because the current is a sine wave, the current is the gain of the system output response function at a single-point frequency, and the gain is a constant value; that is, k is a fixed parameter once the frequency f is determined. Then there are

V_o＝g·V_busTherefore, the bus voltage and the output voltage have a linear relation, and the output voltage can be changed by changing the bus voltage.

As shown in fig. 3 and 4, for the soft switching control of the inverter, first, the frequency of the inverter is near the resonant frequency, the current-voltage phase is the same at the resonant frequency point, the frequency is near the resonant frequency, and it is satisfied that the current phase is slightly later than the voltage phase; at the time 0-t0, the current is positive, the upper tube is on, at the time t0, the voltage drop of the upper tube is about 0, the current is about 0, and at the time t0, the upper tube is off, which meets the requirements of zero voltage and zero current off; at the time t0-t2, the current is about 0, the tube diode is in follow current, the voltage drop is the diode voltage drop which is about 0, the current is about 0, the tube is switched on at the time t2, and the zero voltage and zero current switching is met; at the time of t2-t3, the lower tube is switched on, the current is negative, at the time of t3, the voltage drop of the lower tube is about 0, the current is about 0, and the lower tube is switched off at the time of t3, so that zero voltage and zero current switching are met; at time t3-t5, the current is about 0, the tube diode freewheels, the voltage drop is the diode voltage drop which is about 0, the current is about 0, and the tube is turned on at time t5, which meets the conditions of zero voltage and zero current; in conclusion, the on and off of the upper and lower tubes of the bridge arm both meet the soft switching characteristics of zero voltage and zero current.

For a better understanding of the present invention, the following are specific applications of the present invention:

as shown in fig. 5, the input power of the high-voltage direct-current power supply control system is supplied by a storage battery, the output voltage can reach 10kv, the DC/DC is a boost topology, and the output voltage (i.e., the bus voltage) is changed by changing the off time in a constant on-time control mode, i.e., a COT control method; the output voltage of the Boost is 4V-16V, and the Boost frequency range is 1MHz-2 MHz.

As shown in fig. 5, the output voltage is controlled by feeding back the output voltage through the resistance voltage-dividing sampling circuit, comparing the output voltage with a reference given signal, and obtaining a reference given signal of boost through the first-stage PI compensation network; the bandwidth of the first-stage PI compensation network is 500Hz, which is far lower than the bandwidth of Boost by more than 50 kHz; the second stage compensation network outputs a compensation signal, controls the off time of the PWM through the COT controller, and adjusts the output voltage of the boost, namely the bus voltage.

According to the above description, the whole output voltage regulating system of the present invention is a closed loop system.

The inverter adopts a full-bridge structure, a switch tube is an MOSFET (metal oxide semiconductor field effect transistor), rdson is 100 milliohms, an LC (inductance-capacitance) network is only one blocking capacitor Cb, the turn ratio of the transformer is 60, primary side inductance is 36uH, leakage inductance is 6uH, secondary side leakage inductance is 18mH, and secondary side equivalent parallel capacitance is 10 pF.

The resonance frequency of the system is 26kHz, when the frequency is more than 26kHz, the system presents inductance, namely current lags behind voltage, the working frequency is 26.5kHz, and the current slightly lags behind the voltage.

The secondary side is 8 times of voltage-multiplying rectification output; the dead time (including rising edge and falling edge) of the bridge arm is 0.6us (namely the time of t2-t0, t5-t 3), the current at the time of t0 is 193mA, and the voltage of the two ends of the switching tube is about 20 mV; at the time of t2, the current is-314 mA, and the voltage at two ends of the switching tube is-520 mV; the current at the time t3 is-215 mA, and the voltage at the two ends of the switching tube is-22 mV; the current at the time t5 is 324mA, and the voltage at the two ends of the switching tube is 520 mV; the voltage and the current at the moment when the switching tube is switched off and switched on are very small, so that the switching tube can be regarded as a soft switch with zero voltage and zero current.

The above embodiments are only for illustrating the invention and are not to be construed as limiting the invention, and those skilled in the art can make various changes and modifications without departing from the spirit and scope of the invention, therefore, all equivalent technical solutions also belong to the scope of the invention, and the scope of the invention is defined by the claims.