CN102828983A - Fan cooling control device and working method thereof - Google Patents

Abstract

The invention relates to a fan cooling control device, comprising: a temperature detection sensor, several fans, and a PLC module connected with the temperature detection sensor and suitable for controlling the operation of a corresponding number of fans and the corresponding speed of the fans according to the external temperature. The present invention uses the PLC module to replace the traditional relay circuit, which avoids the defects of cumbersome wiring and high relay failure rate; controls the number of fans and the number of rotations according to the temperature, and does not start the fan or a small number of fans in the winter when the temperature is low. The number of revolutions is slow, and in summer when the temperature is high, all the fans need to be started to dissipate heat and the number of revolutions should be increased according to the specific temperature, so the device saves a lot of electric energy and prolongs the life of the motor.

Description

Fan cooling control device and working method thereof

technical field

The invention relates to a fan cooling control device and a working method thereof.

Background technique

In the prior art, transformers with a voltage level of 110kV and below often use a cooling fan to cool the transformer, and the working condition of the cooling fan directly affects the load capacity of the transformer; and the fan cooling control device often fails, according to statistics , the failure of the fan cooling control device is mainly divided into control loop and component failure, and the main reason for the control loop failure is that the control component uses an electromagnetic relay. Poor capacity causes these components to be often burned and damaged, which affects the operation of the air-cooled system. Therefore, how to design a replacement electromagnetic relay to control the entire fan cooling control device is a technical problem in this field.

Contents of the invention

The technical problem to be solved by the present invention is to provide a control device suitable for detecting ambient temperature to control fan cooling.

In order to solve the above technical problems, the present invention provides a fan cooling control device, including: a temperature detection sensor, a number of fans, connected to the temperature detection sensor and suitable for controlling the operation of a corresponding number of fans according to the external temperature and the corresponding speed of the fans PLC module.

Furthermore, because the motor is an inductive load, it will increase the reactive power of the grid during use and reduce the power factor. Therefore, it is necessary to use chained SVG (static var generator, also known as Static synchronous compensator) control device to improve the power factor in the power grid, so the fan cooling control device also includes: a chained SVG control device suitable for correcting power factor, the chained SVG control device is connected to the Input for the three-phase power supply to the fan cooling control unit.

Further, in order to automatically bypass the failed H-bridge unit circuit to ensure the normal operation of the H-bridge multi-connected multi-level inverter, so that the chained SVG control device can continue to achieve the purpose of correcting the power factor, the Chained SVG controls include:

对各H电桥单元电路之间采用的载波三角波移相SPWM进行控制；即，当损坏的H电桥单元电路旁路后，该脉宽调制电路适于在保持所述采样电路的采样周期不变的基础上，改变该损坏的H电桥单元电路所在的一相H桥功率模块的所述载波三角波移相SPWM的载波频率，以获得与该相H桥功率模块中剩余的H电桥单元电路数量相对应的载波三角波移相SPWM的脉冲调制波形。 H-bridge multi-connected multi-level inverter, which is composed of three-phase H-bridge power modules connected to the three-phase power supply, wherein, at least one spare H-bridge unit circuit is added to each phase H-bridge power module ; The automatic bypass circuit is located at the output end of each H bridge unit circuit, and when an H bridge unit circuit is damaged, the H bridge unit circuit is bypassed; the sampling circuit is suitable for collecting the three-phase The instantaneous value of the voltage and current of the power supply; the independent control circuit of the phase-splitting current, which is connected to the sampling circuit and is suitable for calculating the required voltage of the pulse width modulation circuit according to the instantaneous value of the voltage and current of the three-phase power supply Modulation ratio M and phase angle of sinusoidal modulation wave ; The pulse width modulation circuit is connected with the independent control circuit of the phase-splitting current, and is used for modulation ratio M and phase angle according to the sinusoidal modulation wave

The carrier triangular wave phase-shifting SPWM adopted between each H bridge unit circuit is controlled; that is, after the damaged H bridge unit circuit is bypassed, the pulse width modulation circuit is suitable for keeping the sampling period of the sampling circuit constant. On the basis of the change, change the carrier frequency of the carrier triangular wave phase-shifting SPWM of the phase-shifted SPWM of the one-phase H-bridge power module where the damaged H-bridge unit circuit is located, so as to obtain a The pulse modulation waveform of the phase-shifted SPWM of the carrier triangular wave corresponding to the number of circuits.

Further, the phase-splitting current independent control circuit includes:

。 A phase-locked loop, tracking the voltage phase of the three-phase power supply according to the instantaneous value of the voltage of the three-phase power supply; a reactive current given module, adapted to calculate the voltage according to the voltage phase obtained by the phase-locked loop The cosine of the phase is multiplied by a reactive current reference value to obtain the actual reactive current output; the active current given module is suitable for calculating the sine of the voltage phase according to the voltage phase obtained by the phase-locked loop At the same time, according to the average voltage of the DC side capacitors of the H-bridge power modules of each phase, the voltage reference value of a DC side capacitor is subtracted and then multiplied by the sine quantity after PI control to obtain the actual active power Current output; an instantaneous current tracking module, used to first superimpose the currents output by the reactive current given module and the active current given module, then subtract the instantaneous current in the three-phase power supply, and use the controller to calculate The modulation ratio M and the phase angle of the sinusoidal modulation wave required by the pulse width modulation circuit

.

Compared with the prior art, the fan cooling control device of the present invention has the following advantages: (1) The PLC module is used to replace the traditional relay circuit, which avoids the defects of cumbersome wiring and high failure rate of the relay; The control of the number and the number of revolutions, in winter when the temperature is low, it is not necessary to start the fan or a small number of fans and the number of revolutions is slow. The device saves a lot of electric energy, and also prolongs the life of the motor; (3) Using the chained SVG control device, corrects the problem of the power factor drop of the power grid caused by the operation of the motor, and improves the utilization rate of the transformer; (4) in The chain-type SVG control device is provided with a spare H-bridge unit circuit, which can automatically bypass the faulty H-bridge unit circuit when another H-bridge unit circuit fails, and ensure that the H-bridge multi-connected multi-level The inverter works normally, that is, to correct the power factor of the power grid; (5) and when the H-bridge power module is damaged, there is no need to stop for maintenance, which ensures the stability of the power grid; (6) The pulse width modulation circuit adjusts the damaged phase The modulation wave of the H-bridge power module effectively avoids the generation of harmonics; (7) The compensation problem of the unbalanced output of the three-phase power supply is realized through the independent control of the phase-separated current.

the

The technical problem to be solved by the present invention is to provide a kind of H-bridge unit circuit suitable for automatic bypass fault on the basis of the fan cooling control device, so as to ensure the normal operation of the H-bridge multi-connected multi-level inverter. Working method of chained SVG controls.

In order to solve the above problems, the working method of the fan cooling control device includes:

The working method of described chain type SVG control device, it comprises the steps:

A: When an H bridge unit circuit is damaged, the corresponding automatic bypass circuit bypasses the H bridge unit circuit;

B: on the basis of keeping the sampling period of the sampling circuit constant, the pulse width modulation circuit changes the carrier triangular wave phase-shifting SPWM of the one-phase H bridge power module where the damaged H bridge unit circuit is located Carrier frequency, to obtain the pulse modulation waveform of the carrier triangular wave phase-shifting SPWM corresponding to the remaining H bridge unit circuit quantity in the phase H bridge power module;

The working method of the phase-splitting current independent control circuit comprises the following steps:

(1) tracking the voltage phase of the three-phase power supply according to the instantaneous value of the input voltage of the three-phase power supply through a phase-locked loop;

(2) Calculate the cosine value of the voltage phase according to the voltage phase obtained by the phase-locked loop and multiply it with a reactive current reference value to obtain the actual reactive current output;

(3) Calculate the sine quantity of the voltage phase according to the voltage phase obtained by the phase-locked loop, and at the same time, according to the average voltage of the DC-side capacitor of the H-bridge power module of each phase and the voltage reference value of a DC-side capacitor After subtraction and multiplication with the sine quantity after PI control, to obtain the actual active current output;

。 (4) It is used to superimpose the output currents of the reactive current given module and the active current given module first, then subtract the instantaneous current in the three-phase power supply, and calculate the pulse width through the controller The modulation ratio M and phase angle of the sinusoidal modulation wave required by the modulation circuit

.

the

Compared with the prior art, the working method of the chained SVG control device in the working method of the fan cooling control device of the present invention has the following advantages: (1) By adding at least one standby power module in each phase H-bridge power module H-bridge unit circuit, when the H-bridge power module is damaged, it will automatically bypass the faulty module without shutting down for maintenance; (2) The pulse width modulation circuit adjusts the modulated wave of the damaged one-phase H-bridge power module, effectively avoiding Harmonic generation; (3) The compensation problem of unbalanced output of three-phase power supply is realized through independent control of phase-separated current.

the

Description of drawings

In order to make the content of the present invention more easily understood, the present invention will be described in further detail below in conjunction with the specific embodiments according to the accompanying drawings, wherein

Fig. 1 is the structural block diagram of fan cooling control device of the present invention;

Fig. 2 is a structural block diagram of the chained SVG control device of the present invention;

The circuit structure diagram of the multi-level inverter of the multi-connection type of H electric bridge of the present invention of Fig. 3;

The block diagram of the structure of the independent control circuit of phase-splitting current of Fig. 4 of the present invention;

The oscillogram of carrier triangular wave in-phase single-layer laminated SPWM modulation of Fig. 5 of the present invention;

Fig. 6 The timing sequence of pulse generation before the failure of the H-bridge unit module of the present invention;

The timing sequence of pulse generation after the first fault H bridge unit module of the present invention is bypassed in Fig. 7;

FIG. 8 is the timing sequence of pulse generation after the second faulty H-bridge unit module of the present invention is bypassed.

Detailed ways

Below in conjunction with accompanying drawing and embodiment the present invention is described in detail:

Example 1

As shown in Figure 1, a fan cooling control device, a fan cooling control device, includes: a temperature detection sensor, a number of fans, connected to the temperature detection sensor and is suitable for controlling the corresponding number of fans according to the external temperature and the corresponding speed of the fans PLC module. In the summer when the temperature of the fan is high, the heat generated by the transformer is huge, so when the temperature detected by the sensor reaches 60 degrees Celsius, all the fans are working, and the fan speed can be increased according to the ambient temperature; in winter with a low temperature, due to the ambient temperature Low, so when the calorific value of the transformer is not high, the fan can be turned on less or not, and the rotation speed of the fan can be appropriately reduced.

As shown in Figure 2, the fan cooling control device fan cooling control device also includes: a chain SVG control device suitable for power factor correction, the chain SVG control device is connected to the input of the three-phase power supply of the fan cooling control device end.

As shown in Figures 2 and 3, the chained SVG control device includes:

H-bridge multi-connected multi-level inverter, which is composed of three-phase H-bridge power modules connected to the three-phase power supply, wherein, at least one spare H-bridge unit circuit is added to each phase H-bridge power module ;

An automatic bypass circuit is set at the output end of each H-bridge unit circuit, and when an H-bridge unit circuit is damaged, the H-bridge unit circuit is bypassed;

The sampling circuit is suitable for collecting the instantaneous value of the voltage and current of the three-phase power supply, the instantaneous value includes the amplitude and period of the voltage and current;

； Separate phase current independent control circuit, which is connected to the sampling circuit and is suitable for calculating the modulation ratio M and phase of the sinusoidal modulation wave required by the pulse width modulation circuit according to the instantaneous value of the voltage and current of the three-phase power supply horn

;

对各H电桥单元电路之间采用的载波三角波移相SPWM进行控制；即，当损坏的H电桥单元电路旁路后，该脉宽调制电路适于在保持所述采样电路的采样周期不变的基础上，改变该损坏的H电桥单元电路所在的一相H桥功率模块的所述载波三角波移相SPWM的载波频率，以获得与该相H桥功率模块中剩余的H电桥单元电路数量相对应的载波三角波移相SPWM的脉冲调制波形。 A pulse width modulation circuit, connected to the phase-splitting current independent control circuit, is used for adjusting the modulation ratio M and the phase angle according to the sinusoidal modulation wave

The carrier triangular wave phase-shifting SPWM adopted between each H bridge unit circuit is controlled; that is, after the damaged H bridge unit circuit is bypassed, the pulse width modulation circuit is suitable for keeping the sampling period of the sampling circuit constant. On the basis of the change, change the carrier frequency of the carrier triangular wave phase-shifting SPWM of the phase-shifted SPWM of the one-phase H-bridge power module where the damaged H-bridge unit circuit is located, so as to obtain a The pulse modulation waveform of the phase-shifted SPWM of the carrier triangular wave corresponding to the number of circuits.

As shown in Fig. 4, the independent control circuit of the split-phase current includes:

a phase-locked loop, tracking the voltage phase of the three-phase power supply according to the instantaneous value of the voltage of the three-phase power supply;

The reactive current given module is adapted to calculate the cosine of the voltage phase according to the voltage phase obtained by the phase-locked loop and multiply it with a reactive current reference value to obtain the actual reactive current output;

The active current given module is adapted to calculate the sine quantity of the voltage phase according to the voltage phase obtained by the phase-locked loop, and at the same time according to the average voltage and a DC side capacitance of the H-bridge power module of each phase The voltage reference value of the capacitor is subtracted and then multiplied by the sine quantity after PI control to obtain the actual active current output;

。 The instantaneous current tracking module is used to superimpose the output currents of the given reactive current module and the given active current module, then subtract the instantaneous current in the three-phase power supply, and calculate the The modulation ratio M and phase angle of the sinusoidal modulation wave required by the pulse width modulation circuit

.

Wherein the reference current is an expected compensation current, and the DC voltage reference value is an expected compensation voltage.

The pulse width modulation circuit relates to the SPWM pulse width modulation method. The SPWM pulse width modulation method uses a sine wave as a modulation wave, and uses a triangular wave with F times the frequency of the sine modulation wave as a carrier wave to perform waveform comparison. Equal, the width is proportional to the rectangular pulse train of the sinusoidal modulation wave to be equivalent to the sine wave, thereby controlling the on-off of the switching device (that is, the switching device in the multi-level inverter).

The present invention adopts the hybrid control algorithm of carrier triangular wave phase-shifting SPWM control and carrier triangular wave stacked SPWM control: on the whole, carrier triangular wave phase-shifting SPWM control is adopted between each H bridge unit circuit, and a single H bridge unit circuit adopts The stacked SPWM control method, this modulation method has small output harmonic content, low switching frequency, and can well solve the problem of low inverter efficiency.

Carrier triangular wave phase-shifting SPWM control method means that for N H-bridge unit circuits, N sets of SPWM control pulses are generated by comparing N carrier triangular waves with the same frequency and amplitude with the same sine modulating wave. The waveforms are used to control the N H-bridges, so that each H-bridge unit circuit outputs the SPWM voltage waveform with the same fundamental voltage, and then the SPWM voltage waveforms output by the N H-bridge unit circuits are superimposed to synthesize a multi-SPWM level voltage waveform.

；若是单极性载波三角波，角度为。 The initial phase angles of the N carrier triangular waves should be shifted by an angle in turn. If a bipolar carrier triangular wave is used, the angle is

; If it is a unipolar carrier triangle wave, the angle is .

Carrier triangular wave stacked SPWM control method is a kind of SPWM modulation method of multi-level inverter that was applied relatively early. The carrier triangular wave stacked SPWM modulation method can be divided into two types, that is, a single-layer stacked SPWM modulation method and a multi-layer stacked SPWM modulation method, both of which can achieve the technical effect of this patent.

Carrier triangular wave single-layer stacked SPWM modulation method can be divided into carrier triangular wave anti-phase single-layer stacked SPWM modulation method (the phase of two carrier triangle waves is opposite) and carrier triangular wave in-phase single-layer stacked SPWM modulation method according to the phase relationship of two triangular carrier waves (The two carrier triangle waves have the same phase). Carrier triangular wave anti-phase single-layer stacked SPWM modulation method and carrier triangular wave in-phase single-layer stacked SPWM modulation method have no advantages or disadvantages. The present invention adopts carrier triangular wave in-phase single-layer stacked SPWM modulation method.

和

的相位相同，其工作波形如图5所示。其中

和

为横轴上、下层的载波三角波，

为正弦调制波。用正弦波与三角波进行比较，在正弦波

大于三角波的部分会产生输出SPWM脉冲，在正弦波小于三角波的部分会产生输出电压的零脉冲。由于

与

是同相的，也就是说

与

不对称于坐标横轴，所以通过正弦波与三角波的比较，产生的输出电压SPWM波形的正半周与负半轴是不相同的。 In the carrier triangular wave in-phase single-layer stacked SPWM modulation method, two carrier triangular waves

and

The phase is the same, and its working waveform is shown in Figure 5. in

and

is the carrier triangle wave on the upper and lower layers of the horizontal axis,

is a sine wave. Compared with a sine wave and a triangle wave, in the sine wave

The part greater than the triangular wave will generate an output SPWM pulse, in the sine wave The part smaller than the triangular wave will produce a zero pulse of the output voltage. because

and

are in phase, that is,

and

It is asymmetrical to the horizontal axis of the coordinates, so by comparing the sine wave and the triangular wave, the positive half cycle and the negative half axis of the output voltage SPWM waveform are different.

为H电桥单元电路的输出电压，

为相电流，

为输出电压和相电流的夹角，则H电桥单元电路吸收的有功功率为：

，可见，通过改变H电桥单元电路输出电压大小、相电流大小以及它们之间的夹角就能够改变H桥吸收的有功功率。因为相电流 

 的大小和方向固定，所以只能改变H电桥单元电路输出电压的大小和方向，即对应到脉宽调制电路输出的调制比M和移相角

。 Take any H bridge unit circuit for research, and analyze it from the perspective of power. set up

is the output voltage of the H-bridge unit circuit,

is the phase current,

is the angle between the output voltage and the phase current, then the active power absorbed by the H-bridge unit circuit is:

, it can be seen that the active power absorbed by the H bridge can be changed by changing the output voltage of the H bridge unit circuit, the phase current and the angle between them. Because the phase current

The magnitude and direction of the voltage are fixed, so only the magnitude and direction of the output voltage of the H bridge unit circuit can be changed, that is, the modulation ratio M and the phase shift angle corresponding to the output of the pulse width modulation circuit

.

The control strategy of the chained SVG adopts a hierarchical control structure: the upper layer control mainly determines the total active and reactive power, and the lower layer control mainly adjusts the reasonable distribution of active power among the H-bridges of the phase to ensure the DC side capacitor voltage balance. The upper layer control method of the present invention adopts independent control of the phase-separated current, calculates the modulation ratio and phase angle of the expected modulation wave, quantizes the error of the DC side voltage of each bridge into a sinusoidal function and superimposes it on the modulation wave of the H-bridge unit circuit , to fine-tune the phase of the modulated wave of each H-bridge unit circuit, and adjust the distribution of active power among the H-bridge unit circuits.

There is no coupling relationship on the three-phase DC side of the chain-type SVG, so phase-separated control can be realized, and the three-phase system can be compensated separately, and it can have a better compensation effect on both balanced and unbalanced systems. In the control strategy proposed in the previous section, the upper layer control adopts the complete decoupling control of the current state, the transient response is fast, and the stability is good, but the controller design only considers the situation when the three-phase balance is not considered. A matter of balance. The investigation of the power grid quality shows that the grid voltage is more or less asymmetrical in phase or amplitude, that is to say, in actual situations, the three-phase system is mostly unbalanced.

The automatic bypass circuit adopts automatic bypass technology, which is to directly bypass the AC side of the faulty power module, so as to realize the separation of the faulty module and the device. Automatic bypass is realized by setting a bypass mechanism on the output side of each power unit module.

A relay can be provided at the output end of each H-bridge unit circuit, and the faulty H-bridge unit circuit can be separated from the H-bridge power module of the phase by controlling the normally open and normally closed states; a rectifier bridge and a thyristor can also be used, each The output of the H-bridge unit circuit is connected to the rectifier bridge composed of two pairs of diodes, so the thyristor is always under the forward voltage drop. When the monitoring system detects an internal fault in the power module, it immediately blocks the IGBT pulse and triggers the thyristor to conduct to realize bypass separation; or use a bidirectional thyristor.

When the faulty H bridge unit circuit in a certain phase H bridge power module is bypassed, if the pulse transmission of the sinusoidal modulation signal output by the pulse width modulation circuit is still transmitted according to normal operation, and the output of the chain SVG control system However, only N H bridge unit circuit output voltages are superimposed, and the harmonic content will increase. Therefore, for the remaining N non-faulty H-bridge unit circuits, the modulation strategy needs to be adjusted accordingly.

Because the carrier triangular wave stacked SPWM only works inside a single H-bridge unit circuit, the separation of the faulty module has no effect on the carrier triangular wave stacked SPWM modulation, and only affects the carrier triangular wave phase-shifting SPWM. Therefore, for the convenience of analysis, only the phase-shifted SPWM of the carrier triangular wave is analyzed. Assume that when N+1 H bridge unit circuits are connected in series, the carrier frequency of the chained SVG control system is 1/T _c , the sampling period is T _s , and when the carrier is unipolar, the sampling period T _s = T _c /[ 2(N+1)] . Two commonly used adjustment methods after the faulty H bridge unit circuit is separated are given below.

The first method: T _c does not change, T _s changes

In order to simplify the analysis, before selecting the fault, assuming that the number of multilevel inverters is n+1=6, then the sampling period T _s =T _c /12 of the H-bridge power module of each phase, at 0/6T _s , T _s /7T _s , 2T _s /8T _s , 3T _s /9T _s , 4T _s /10T _s , 5T _s /11T _s samples the modulated wave once, and compare them to generate corresponding trigger pulses, as shown in Figure 6.

If a certain H-bridge unit circuit is separated due to a fault (assuming that the first H-bridge unit circuit is separated), if the modulation strategy is not adjusted accordingly, the pulse generation of the remaining N non-faulty H-bridge unit circuits Timing is shown in Fig. 7(a). It can be seen from the figure that the sampling interval between H-bridge unit circuit 0 and H-bridge unit circuit 2 is 2T _s , but the sampling interval between other power H-bridge unit circuits is T _s , which obviously does not conform to the carrier The basic principle of phase shift SPWM modulation. The harmonic content of the output voltage of the SVG device necessarily increases.

Assuming that the carrier period remains unchanged, it is still T _c , but the sampling period is readjusted within T _c . As shown in FIG. 7( b ), since the number of the multilevel inverters becomes 5 after the fault, the sampling period after modulation is T _s ′=T _c /10. This will generate N=5 complete carrier phase-shifted output pulses.

In this method, the switching modulation strategy of the phase-carrier phase-shifting SPWM is adjusted by changing the sampling period of the faulty phase (the one-phase H-bridge power module where the faulty H-bridge unit circuit is located). For this phase, it can play a very good regulating role.

The second method: T _c changes, T _s does not change

When the first H bridge unit circuit breaks down and is separated, keep the sampling period T _s unchanged, and adjust the carrier triangular wave period of this phase. As shown in Figure 8.

The carrier period of the faulty phase after adjustment is Tc', and the carrier period Tc of other non-faulty phases remains unchanged. The adjusted pulse timing is shown in Fig. 8(b): At the time of 0/5Ts, Ts/6Ts, 2Ts/7Ts, 3Ts/8Ts, 4Ts/9Ts, the trigger pulse of the H-bridge power module is generated by sampling the modulated wave once. In this way, a complete N=5 carrier phase-shifted SPWM pulse modulation waveform is obtained. Since the sampling period of the fault phase does not change before and after the fault module is separated, the synchronization of the three-phase current sampling can still be guaranteed after the fault is separated.

、

、

、为采集电路采集到三相电压瞬时值；

、、

为PLL跟踪到的三相电源的电压相位； 

、

、

、为各相无功电流参考值；

、、

为各相H桥功率模块的直流侧电容的电压平均值；

直流侧电容的电压参考值；、

、

为采集电路采集到三相电流瞬时值；通过相应的PI控制器可以计算SVG输出电压的参考信号，再进一步根据瞬时无功理论计算出相应的各相无功电流参考值和直流侧电容的电压参考值。上述获得各相无功电流参考值和直流侧电容的电压参考值的具体方法详见文献：杨君,王兆安,邱关源.单相电路谐波及无功电流的一种检测方法[J],电工技术学报,1996(3),11(3):42-46；蒋斌, 颜钢锋, 赵光宙. 单相电路瞬时谐波及无功电流实时检测新方法[J].电力系统自动化，2000(11):36-39。 The working method of the phase-splitting current independent control circuit. See Figure 4, in which

,

,

, Acquiring the instantaneous value of the three-phase voltage for the acquisition circuit;

, ,

is the voltage phase of the three-phase power tracked by the PLL;

,

,

, is the reference value of reactive current of each phase;

, ,

is the average voltage of the DC side capacitors of the H-bridge power modules of each phase;

The voltage reference value of the DC side capacitor; ,

,

The instantaneous value of the three-phase current is collected for the acquisition circuit; the reference signal of the SVG output voltage can be calculated through the corresponding PI controller, and the corresponding reactive current reference value of each phase and the voltage of the DC side capacitor can be further calculated according to the instantaneous reactive power theory Reference. For the specific method of obtaining the reference value of the reactive current of each phase and the voltage reference value of the DC side capacitor, please refer to the literature: Yang Jun, Wang Zhaoan, Qiu Guanyuan. A detection method for harmonics and reactive current of single-phase circuits[J], Electrician Journal of Technology, 1996(3), 11(3):42-46; Jiang Bin, Yan Gangfeng, Zhao Guangzhou. A new method for real-time detection of instantaneous harmonics and reactive current in single-phase circuits [J]. Electric Power System Automation, 2000(11) :36-39.

the

Example 2

See Figures 2-4, on the basis of Embodiment 1, the working method of the air-cooled control device includes:

The working method of the chained SVG control device provided at the three-phase power supply of the control device comprises the following steps:

A: When an H bridge unit circuit is damaged, the corresponding automatic bypass circuit bypasses the H bridge unit circuit;

B: on the basis of keeping the sampling period of the sampling circuit constant, the pulse width modulation circuit changes the carrier triangular wave phase-shifting SPWM of the one-phase H bridge power module where the damaged H bridge unit circuit is located Carrier frequency, to obtain the pulse modulation waveform of the carrier triangular wave phase-shifting SPWM corresponding to the remaining H bridge unit circuit quantity in the phase H bridge power module;

The working method of the phase-splitting current independent control circuit comprises the following steps:

(1) tracking the voltage phase of the three-phase power supply according to the instantaneous value of the input voltage of the three-phase power supply through a phase-locked loop;

(2) Calculate the cosine value of the voltage phase according to the voltage phase obtained by the phase-locked loop and multiply it with a reactive current reference value to obtain the actual reactive current output;

(3) Calculate the sine quantity of the voltage phase according to the voltage phase obtained by the phase-locked loop, and at the same time, according to the average voltage of the DC-side capacitor of the H-bridge power module of each phase and the voltage reference value of a DC-side capacitor After subtraction and multiplication with the sine quantity after PI control, to obtain the actual active current output;

。 (4) It is used to superimpose the output currents of the reactive current given module and the active current given module first, then subtract the instantaneous current in the three-phase power supply, and calculate the pulse width through the controller The modulation ratio M and phase angle of the sinusoidal modulation wave required by the modulation circuit

.

the

Apparently, the above-mentioned embodiments are only examples for clearly illustrating the present invention, rather than limiting the implementation of the present invention. For those of ordinary skill in the art, other changes or changes in different forms can be made on the basis of the above description. It is not necessary and impossible to exhaustively list all the implementation manners here. And these obvious changes or modifications derived from the spirit of the present invention are still within the protection scope of the present invention.

Claims (5)

1. blower fan cooling controller is characterized in that comprising: temperature detection sensor, some blower fans, being suitable for of linking to each other with said temperature detection sensor are just controlled the blower fan work of respective numbers and the PLC module of the corresponding rotating speed of blower fan according to external temperature.

2. blower fan cooling controller according to claim 1 is characterized in that also comprising: one is suitable for correcting the chain type SVG control gear of power factor, and this chain type SVG control gear is connected in the input end of the three phase mains of said blower fan cooling controller.

3. blower fan cooling controller according to claim 2 is characterized in that, said chain type SVG control gear comprises:

The multi-electrical level inverter of H electric bridge multi-type, it is made up of the three-phase H bridge power model that is connected in said three phase mains, wherein, sets up at least one subsequent use H electric bridge element circuit in every phase H bridge power model;

The auto by pass circuit is located at the output terminal of each H electric bridge element circuit, and when a H electric bridge element circuit is damaged, with this H electric bridge element circuit bypass;

Sample circuit is suitable for gathering the momentary value of the voltage and current of said three phase mains;

Divide the phase current independent controling circuit, it links to each other with said sample circuit is suitable for calculating according to the momentary value of the voltage and current of said three phase mains modulation ratio M and phase angle

of the required sinusoidal modulation wave of said pulse-width modulation circuit;

Pulse-width modulation circuit; Link to each other with said minute phase current independent controling circuit, be used for the carrier wave pyramidal wave phase shift SPWM that adopts between each H electric bridge element circuit being controlled according to modulation ratio M and phase angle

of said sinusoidal modulation wave; Promptly; After the H electric bridge element circuit bypass that damages; This pulse-width modulation circuit is suitable on the sampling period basis of invariable that keeps said sample circuit; Change the carrier frequency of said carrier wave pyramidal wave phase shift SPWM of a phase H bridge power model at the H electric bridge element circuit place of this damage, to obtain and this Sampling waveform of corresponding carrier wave pyramidal wave of remaining H electric bridge element circuit quantity phase shift SPWM in H bridge power model mutually.

4. blower fan cooling controller according to claim 3 is characterized in that, said minute phase current independent controling circuit comprises:

Phaselocked loop, according to the momentary value of the voltage of said three phase mains to follow the tracks of the voltage-phase of said three phase mains;

The given module of wattless current is suitable for calculating the cosine amount of this voltage-phase and multiplying each other with a wattless current reference value according to the voltage-phase that said phaselocked loop draws, to obtain actual wattless current output;

The given module of active current; Be suitable for calculating the sinusoidal quantity of this voltage-phase according to the voltage-phase that said phaselocked loop draws; Subtract each other simultaneously and, export to obtain actual active current through multiplying each other with said sinusoidal quantity again after the PI control according to the voltage reference value of the average voltage of the dc bus capacitor of said each phase H bridge power model and a direct current lateral capacitance;

The transient current tracking module; Be used for the electric current stack of elder generation with given module of said wattless current and the given module output of active current; Deduct the transient current in the said three phase mains then, and through modulation ratio M and phase angle of controller to calculate the required sinusoidal modulation wave of said pulse-width modulation circuit.

5. the method for work of blower fan cooling controller according to claim 4 comprises:

The method of work of said chain type SVG control gear comprises the steps:

A: when a H electric bridge element circuit damages, corresponding this H electric bridge element circuit of auto by pass circuit bypass;

B: said pulse-width modulation circuit is on the sampling period basis of invariable that keeps said sample circuit; Change the carrier frequency of said carrier wave pyramidal wave phase shift SPWM of a phase H bridge power model at the H electric bridge element circuit place of said damage, to obtain and this Sampling waveform of corresponding carrier wave pyramidal wave of remaining H electric bridge element circuit quantity phase shift SPWM in H bridge power model mutually;

The method of work of said minute phase current independent controling circuit comprises the steps:

(1) follows the tracks of the voltage-phase of said three phase mains according to the momentary value of the voltage of said three phase mains through phaselocked loop;

(2) voltage-phase that draws according to said phaselocked loop calculates the cosine amount of this voltage-phase and multiplies each other with a wattless current reference value, to obtain actual wattless current output;

(3) voltage-phase that draws according to said phaselocked loop calculates the sinusoidal quantity of this voltage-phase; Subtract each other simultaneously and, export to obtain actual active current through multiplying each other with said sinusoidal quantity again after the PI control according to the voltage reference value of the average voltage of the dc bus capacitor of said each phase H bridge power model and a direct current lateral capacitance;

(4) be used for the electric current stack of elder generation with given module of said wattless current and the given module output of active current; Deduct the transient current in the said three phase mains then, and through modulation ratio M and phase angle

of controller to calculate the required sinusoidal modulation wave of said pulse-width modulation circuit.

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