CN117833328A - Electronic equipment and rapid discharging method thereof - Google Patents
Electronic equipment and rapid discharging method thereof Download PDFInfo
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- CN117833328A CN117833328A CN202211199258.XA CN202211199258A CN117833328A CN 117833328 A CN117833328 A CN 117833328A CN 202211199258 A CN202211199258 A CN 202211199258A CN 117833328 A CN117833328 A CN 117833328A
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- 238000000034 method Methods 0.000 title claims description 29
- 239000003990 capacitor Substances 0.000 claims abstract description 37
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- 238000004146 energy storage Methods 0.000 claims description 6
- 238000010586 diagram Methods 0.000 description 6
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- 230000006698 induction Effects 0.000 description 2
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Abstract
There is provided an electronic device, comprising: the direct current bus comprises a positive direct current bus and a negative direct current bus; an inverter including a semiconductor switching device, the inverter comprising: the first input end is used for receiving direct current input from the positive direct current bus, the second input end is used for receiving direct current input from the negative direct current bus, the grounding end is used for being connected to the ground, and the output end is used for outputting inverted alternating current; a first load output; a second load output connected to ground; an inductor coupled between an output of the inverter and the first load output; a first capacitor coupled between the first load output and ground; wherein the electronic device is arranged to control a duty cycle at which the semiconductor switching devices in the inverter are alternately turned on when the electronic device is powered off, such that the inverter operates in a controlled current source mode to shorten the time for discharging the dc bus voltage to a safe voltage.
Description
Technical Field
The present invention relates to the field of electronic circuits, and more particularly, to an electronic device and a rapid discharge method for the electronic device.
Background
When the electronic device is powered down, the capacitor in the system needs to be discharged to a safe level within a certain time, e.g. a capacitor on a dc bus in an uninterruptible power supply.
Taking uninterruptible power supply as an example, the discharging process of the capacitor on the direct current bus is described. Fig. 1 shows a schematic circuit diagram of an uninterruptible power supply having an inverter function portion. As shown in fig. 1, the uninterruptible power supply includes a direct current bus, an inverter, energy storage capacitors C2, C3, an inductor L1, and a capacitor C1. Wherein the dc BUS is for receiving dc inputs, comprising a positive dc BUS + BUS connected to a positive dc input IN1 and a negative dc BUS-BUS connected to a negative dc input IN 2. The switching tubes Q1, Q2, Q3, Q4 and the diodes D1, D2 form an inverter, and the inverter comprises a first input end for receiving direct current input from a positive direct current BUS +BUS; a second input for receiving a dc input from a negative dc BUS-BUS; a ground terminal for connection to Ground (GND); and an output terminal for outputting the inverted alternating current to the first load output terminal OUT1. The second load output terminal OUT2 is connected to ground. A second capacitor C2 is coupled between the positive dc BUS + BUS and ground; a third capacitor C3 is coupled between the negative dc BUS-BUS and ground; the inductor L1 is coupled between the output of the inverter and the first load output OUT 1; the first capacitor C1 is coupled between the first load output terminal OUT1 and ground.
The switching tubes Q1, Q2 in the inverter are connected in series, the switching tubes Q3, Q4 are connected in series, and the two groups of switching tubes are alternately conducted by controlling the gate terminals of the switching tubes Q1, Q2, Q3, Q4 so as to invert the direct current into the alternating current.
When the uninterruptible power supply receives a power-off instruction, the dc bus still has a higher voltage value due to the energy storage effect of the second capacitor C2 and the third capacitor C3, so that the dc bus voltage needs to be discharged to a safe voltage within a predetermined period of time. Specifically, the ups turns on the inverter and the voltage on the dc bus discharges through the inverter, the inductor L1, the first capacitor C1 and the ground leg until the dc bus voltage is below the safe value, at which point the inverter is turned off. In the discharging process of the direct current bus, the inverter controls the output voltage of the inverter to be sine wave, and the duty ratio of the alternate conduction of the switching tubes Q1 and Q2 and the switching tubes Q3 and Q4 is calculated, and at the moment, the inverter is in a controlled voltage source mode.
Fig. 2 shows a schematic diagram of the control principle of the discharge process in the controlled voltage source mode. As shown in fig. 2, vref1 is a target voltage value at two ends of a preset first capacitor C1, vbus is an actual bus voltage value measured in real time, and the duty ratio may be calculated according to Vref 1/Vbus. Wherein the target voltage value Vref1 is a sine wave, which can be achieved by multiplying the peak voltage value Vpeak of the target voltage value Vref1 by the unit sine wave Sin. The duty ratio of the switching tubes Q1, Q2 and the switching tubes Q3, Q4 which are alternately conducted can be calculated through a preset target voltage value Vref1, and then the inverter is controlled to be in a controlled voltage source mode.
Fig. 3A shows the discharge current and voltage curves actually measured in the controlled voltage source mode, wherein curve a represents the voltage value on the first capacitor C1, and it can be seen from curve a that the voltage value on the first capacitor C1 is a sine wave; and curve B represents the current value on inductor L1. The lower part of fig. 3A shows an enlarged discharge current and voltage curve. Fig. 3B shows the actual measured discharge time in the controlled voltage source mode, wherein the time for the dc bus voltage to discharge to the safe voltage is 48s. Measurements were made using the PT3000 3K model in both fig. 3A and 3B.
It is assumed that the energy that the dc bus needs to release is constant. Fig. 4A shows the discharge current of the switching tube calculated in the controlled voltage source mode, the ordinate of which is the current of the switching tube Q1, Q2 or the switching tube Q3, Q4, and the abscissa of which is time, the loss of the switching tube Q1, Q2, Q3, Q4 is 2.181W. Fig. 4B shows the discharge current of the diode calculated in the controlled voltage source mode, with the current of the diodes D1, D2 on the ordinate and the time on the abscissa, and the loss of the diodes D1, D2 calculated as 2.121W. Fig. 4C shows the calculated discharge current of the inductor in the controlled voltage source mode, with the current of the inductor L1 on the ordinate and time on the abscissa, resulting in a loss of 5.22W for the inductor L1. Fig. 5 shows the dc bus voltage over time during a simulated discharge in a controlled voltage source mode.
As can be seen from the above simulation and actual measurement results, the discharge rate of the discharge by the controlled voltage source mode of the inverter is very slow, because in the controlled voltage source mode the current through the inductor L1, the switching transistors Q1, Q2, Q3, Q4 and the diodes D1, D2 is very small.
Therefore, a method capable of rapid discharge is required.
Disclosure of Invention
In accordance with the above-described problems of the prior art, the present invention provides an electronic apparatus including:
the direct current bus comprises a positive direct current bus and a negative direct current bus and is used for receiving direct current input, wherein an energy storage capacitor is arranged between the direct current bus and the ground;
an inverter including a semiconductor switching device, the inverter comprising:
a first input for receiving a dc input from the positive dc bus;
a second input for receiving a dc input from the negative dc bus;
a ground terminal for connection to ground;
the output end is used for outputting the inverted alternating current;
a first load output;
a second load output connected to ground;
an inductor coupled between an output of the inverter and the first load output;
a first capacitor coupled between the first load output and ground;
wherein the electronic device is arranged to control a duty cycle at which the semiconductor switching devices in the inverter are alternately turned on when the electronic device is powered off, such that the inverter operates in a controlled current source mode to shorten the time for discharging the dc bus voltage to a safe voltage.
In one embodiment, the duty cycle is calculated by:
subtracting a preset target current value flowing through the inductor from an actual current value flowing through the inductor, which is measured in real time, to obtain a difference value;
inputting the difference value into a proportional-integral controller, and calculating to obtain control voltage values at two ends of the inductor through differential control;
adding the control voltage value to the actual voltage value at both ends of the first capacitor to obtain a target voltage value at both ends of the inductor and the first capacitor;
the duty cycle is calculated as the target voltage value divided by the actual bus voltage value.
In one embodiment, the target current value is a square wave.
In one embodiment, the target current value is 30% of the inverter rated current.
In one embodiment, the energy storage capacitor includes a second capacitor coupled between the positive dc bus and ground, and a third capacitor coupled between the negative dc bus and ground.
In one embodiment, the inverter is a type I inverter or a type T inverter.
In one embodiment, the semiconductor switching device is a MOSFET or an IGBT.
In one embodiment, the electronic device is an uninterruptible power supply, a photovoltaic inverter, an off-grid inverter, or a frequency converter.
The invention also provides a rapid discharge method for an electronic device as described above, the method comprising:
the electronic equipment receives a closing instruction and enters a bus discharging process;
calculating a preset target current value flowing through an inductor to obtain a duty ratio of alternating conduction of a semiconductor switching device in an inverter, and controlling the inverter to work in a controlled current source mode;
and when the actual bus voltage value is detected to be lower than the safety value, the inverter is turned off.
In one embodiment, the duty cycle is calculated by:
subtracting the target current value from the real current value measured in real time and flowing through the inductor to obtain a difference value;
inputting the difference value into a proportional-integral controller, and calculating to obtain control voltage values at two ends of the inductor through differential control;
adding the control voltage value to the actual voltage value at both ends of the first capacitor to obtain a target voltage value at both ends of the inductor and the first capacitor;
the duty cycle is calculated as the target voltage value divided by the actual bus voltage value.
According to the electronic equipment and the rapid discharging method, the inverter is switched from the controlled voltage source mode to the controlled current source mode in the discharging process, so that the discharging current is increased, and the time for discharging the direct current bus to the safe voltage is greatly reduced. The time for testing or closing the power supply by the user is shortened, and the user experience is improved.
Drawings
Fig. 1 shows a schematic circuit diagram of an uninterruptible power supply having an inverter function portion.
Fig. 2 shows a schematic diagram of the control principle of the discharge process in the controlled voltage source mode.
Fig. 3A shows the discharge current and voltage curves actually measured in the controlled voltage source mode.
Fig. 3B shows the actual measured discharge time in the controlled voltage source mode.
Fig. 4A shows the calculated discharge current of the switching tube in the controlled voltage source mode.
Fig. 4B shows the calculated discharge current of the diode in the controlled voltage source mode.
Fig. 4C shows the calculated inductor discharge current in the controlled voltage source mode.
Fig. 5 shows the dc bus voltage over time during a simulated discharge in a controlled voltage source mode.
Fig. 6 shows a schematic diagram of the control principle of the discharge process in the controlled current source mode.
Fig. 7A shows the discharge current and voltage curves actually measured in the controlled current source mode.
Fig. 7B shows the discharge time actually measured in the controlled current source mode.
Fig. 8A shows the calculated discharge current of the switching tube in the controlled current source mode.
Fig. 8B shows the calculated discharge current of the diode in the controlled current source mode.
Fig. 8C shows the calculated inductor discharge current in the controlled current source mode.
Fig. 9 shows the dc bus voltage over time during a simulated discharge in two modes.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention will be further described in detail by means of specific embodiments with reference to the accompanying drawings. It should be noted that the examples given herein are for illustration only and are not intended to limit the scope of the present invention.
In order to increase the discharge speed, it is necessary to increase the discharge power, and the most straightforward method is to increase the operating current of the inverter. With continued reference to fig. 1, the rapid discharge method of the present invention will be described with reference to an uninterruptible power supply.
And during normal operation of the uninterruptible power supply, the inverter works in a controlled voltage source mode, and when the uninterruptible power supply receives a command of closing the power supply and enters a bus discharging process, the inverter is converted into a controlled current source mode from the controlled voltage source mode until the direct-current bus voltage is discharged to a safe voltage. In the controlled current source mode, the discharge current can be directly controlled, namely the discharge speed can be directly controlled, so that the discharge current value can be increased in the controlled current source mode to accelerate the discharge process and shorten the discharge time.
When the switching tubes Q1, Q2 and the switching tubes Q3, Q4 of the inverter are alternately conducted at a certain frequency, the load induction coil inductor L1 is supplied with intermediate frequency current, intermediate frequency alternating magnetic flux is generated in the induction coil, the output current waveform is close to a square wave, and the inverter enters a controlled current source mode. Thus, the inverter can be controlled to enter the controlled current source mode by controlling the duty cycle at which the switching transistors Q1, Q2 and the switching transistors Q3, Q4 are alternately turned on.
Fig. 6 shows a schematic diagram of the control principle of the discharge process in the controlled current source mode. As shown in fig. 6, iref is a preset target current value flowing through the inductor L1, and the target current value Iref is a square wave; ifb is the actual current value through inductor L1 measured in real time; ierr is the difference between the target current value Iref and the actual current value Ifb. The difference Ierr is input to a proportional-integral controller PI, and a control voltage value Vi across the inductor L1 is calculated by differential control and added to an actual voltage value Vo across the first capacitor C1 to obtain the inductor L1 and a target voltage value Vref2 across the first capacitor C1. Vbus is the actual bus voltage value measured in real time, and the duty cycle is Vref2/Vbus can be calculated. Therefore, the target voltage value Vref2 across the inductor L1 and the first capacitor C1 is calculated by the preset target current value Iref, and the duty ratio of the switching transistors Q1, Q2 and the switching transistors Q3, Q4 that are alternately turned on is calculated, so as to control the inverter into the controlled current source mode.
Fig. 7A shows a discharge current and voltage curve actually measured in the controlled current source mode, where curve a represents the voltage value across the first capacitor C1 and curve B represents the current value flowing through the inductor L1. The lower part of fig. 7A shows an amplified discharge current and voltage curve, from which curve B it can be seen that the current flowing through the inductor L1 is a square wave. Fig. 7B shows the actually measured discharge time in the controlled current source mode, wherein the time for discharging the dc bus voltage to the safety voltage is 6.866s. Measurements were made using the PT 3000K 3 model in both fig. 7A and 7B. Compared with the situation that the inverter discharges by using a controlled voltage source mode, the time for discharging the DC bus voltage to the safety voltage is reduced from 48s to 6.866s, and the discharging time is greatly reduced.
It is assumed that the energy that the dc bus needs to release is constant. Fig. 8A shows the discharge current of the switching tube calculated in the controlled current source mode, the ordinate of which is the current of the switching tube Q1, Q2 or Q3, Q4, and the abscissa of which is time, and the loss of the switching tube Q1, Q2, Q3, Q4 is 14.972W. Fig. 8B shows the discharge current of the diode calculated in the controlled current source mode, the ordinate of which is the current of the diode D1, D2, and the abscissa of which is time, and the loss of the diode D1, D2 is 3.487W. Fig. 8C shows the discharge current of the inductor calculated in the controlled current source mode, with the current of the inductor L1 on the ordinate and time on the abscissa, and the loss of the inductor L1 calculated to be 7.42W. In the controlled current source mode, the discharge currents of the switching transistors Q1, Q2, Q3, Q4, the diodes D1, D2, and the inductor L1 are all significantly increased, as compared to the case where the inverter discharges using the controlled voltage source mode, so that the losses of the switching transistors Q1, Q2, Q3, Q4, the diodes D1, D2, and the inductor L1 are all significantly increased.
Fig. 9 shows the dc bus voltage over time during a simulated discharge in two modes. As can be seen from fig. 9, in the controlled current source mode, the discharge speed of the dc bus voltage is faster and the time to discharge to the safety voltage is shorter.
According to one embodiment of the present invention, a rapid discharge method for an uninterruptible power supply includes the steps of:
the uninterruptible power supply receives an instruction of closing the power supply and enters a bus discharging process;
calculating a preset target current value Iref flowing through an inductor L1 to obtain the duty ratio of alternately conducting switching tubes Q1 and Q2 and switching tubes Q3 and Q4 in the inverter, so as to control the inverter into a controlled current source mode;
when the actual bus voltage value Vbus is detected to be lower than the safety value, the inverter is turned off.
Preferably, the preset target current value Iref is 30% of the rated current of the inverter.
In the above embodiment, the type I inverter is taken as an example, but the present invention is not limited thereto, and other types of inverters, such as a T-type inverter, can also apply the rapid discharge method of the present invention.
Although the present invention is described by taking an uninterruptible power supply as an example, the present invention is not limited thereto, and any electronic device including a dc bus and an inverter, such as a photovoltaic inverter, an off-grid inverter, a frequency converter, etc., may be applied to the rapid discharge method of the present invention.
According to the electronic equipment and the rapid discharging method, the inverter is switched from the controlled voltage source mode to the controlled current source mode in the discharging process, so that the discharging current is increased, and the time for discharging the direct current bus to the safe voltage is greatly reduced. The time for testing or closing the power supply by the user is shortened, and the user experience is improved.
In one embodiment, the inverter does not output a voltage to the load during discharging, for example, the load may be connected to the first load output terminal OUT1 and the second load output terminal OUT2 through a switch, which may be in an off state during discharging to avoid affecting the load.
In one embodiment, the switching transistors Q11, Q12, Q13, Q14 may include, but are not limited to, MOSFETs, IGBTs.
While the invention has been described in terms of preferred embodiments, the invention is not limited to the embodiments described herein, but encompasses various changes and modifications that may be made without departing from the scope of the invention.
Claims (10)
1. An electronic device, comprising:
the direct current bus comprises a positive direct current bus and a negative direct current bus and is used for receiving direct current input, wherein an energy storage capacitor is arranged between the direct current bus and the ground;
an inverter including a semiconductor switching device, the inverter comprising:
a first input for receiving a dc input from the positive dc bus;
a second input for receiving a dc input from the negative dc bus;
a ground terminal for connection to ground;
the output end is used for outputting the inverted alternating current;
a first load output;
a second load output connected to ground;
an inductor coupled between an output of the inverter and the first load output;
a first capacitor coupled between the first load output and ground;
wherein the electronic device is arranged to control a duty cycle at which the semiconductor switching devices in the inverter are alternately turned on when the electronic device is powered off, such that the inverter operates in a controlled current source mode to shorten the time for discharging the dc bus voltage to a safe voltage.
2. The electronic device of claim 1, wherein the duty cycle is calculated by:
subtracting a preset target current value flowing through the inductor from an actual current value flowing through the inductor, which is measured in real time, to obtain a difference value;
inputting the difference value into a proportional-integral controller, and calculating to obtain control voltage values at two ends of the inductor through differential control;
adding the control voltage value to the actual voltage value at both ends of the first capacitor to obtain a target voltage value at both ends of the inductor and the first capacitor;
the duty cycle is calculated as the target voltage value divided by the actual bus voltage value.
3. The electronic device of claim 2, wherein the target current value is a square wave.
4. The electronic device of claim 2, wherein the target current value is 30% of the inverter rated current.
5. The electronic device of claim 1, wherein the energy storage capacitor comprises a second capacitor coupled between the positive dc bus and ground, and a third capacitor coupled between the negative dc bus and ground.
6. The electronic device of claim 1, wherein the inverter is an I-type inverter or a T-type inverter.
7. The electronic device of claim 1, wherein the semiconductor switching device is a MOSFET or an IGBT.
8. The electronic device of any of claims 1-7, wherein the electronic device is an uninterruptible power supply, a photovoltaic inverter, an off-grid inverter, or a frequency converter.
9. A rapid discharge method for the electronic device of any of claims 1-8, the method comprising:
the electronic equipment receives a closing instruction and enters a bus discharging process;
calculating a preset target current value flowing through an inductor to obtain a duty ratio of alternating conduction of a semiconductor switching device in an inverter, and controlling the inverter to work in a controlled current source mode;
and when the actual bus voltage value is detected to be lower than the safety value, the inverter is turned off.
10. The rapid discharge method of claim 9, wherein the duty cycle is calculated by:
subtracting the target current value from the real current value measured in real time and flowing through the inductor to obtain a difference value;
inputting the difference value into a proportional-integral controller, and calculating to obtain control voltage values at two ends of the inductor through differential control;
adding the control voltage value to the actual voltage value at both ends of the first capacitor to obtain a target voltage value at both ends of the inductor and the first capacitor;
the duty cycle is calculated as the target voltage value divided by the actual bus voltage value.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202211199258.XA CN117833328A (en) | 2022-09-29 | 2022-09-29 | Electronic equipment and rapid discharging method thereof |
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| Application Number | Priority Date | Filing Date | Title |
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| CN202211199258.XA CN117833328A (en) | 2022-09-29 | 2022-09-29 | Electronic equipment and rapid discharging method thereof |
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| CN117833328A true CN117833328A (en) | 2024-04-05 |
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| CN202211199258.XA Pending CN117833328A (en) | 2022-09-29 | 2022-09-29 | Electronic equipment and rapid discharging method thereof |
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- 2022-09-29 CN CN202211199258.XA patent/CN117833328A/en active Pending
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