How to choose the correct ups power inverter mainly pay attention to the following points .
1 , the rated output voltage: within a predetermined fluctuation range of the input DC voltage is allowed , it means that the rated voltage of the inverter should be output . The stability of rated AC power inverters output voltage accuracy is generally defined as follows : In steady-state operation , the voltage fluctuation range should be a limit , such as the deviation does not exceed the rating of ± 3% or ± 5%. Under load mutations or other interfering factors affecting the dynamics of the output voltage deviation should not exceed the rating of ± 8% or ± 10%.
2 , the output voltage imbalance : Under normal operating conditions, the inverter output phase voltage unbalance ( reverse component of the ratio of positive sequence component ) should not exceed a specified value , usually expressed in% as 5 % or 8 %.
3 , the output voltage waveform distortion : When the inverter output voltage is sinusoidal , shall specify the maximum allowable waveform distortion ( or harmonic content ) . Usually to a total distortion of the output voltage waveform that its value should not exceed 5% ( 10% single phase output enable ) .
4 , rated output frequency of the vehicle power inverters inverter output AC voltage frequency should be a relatively stable value , usually frequency 50Hz. Under normal operating conditions the deviation should be within ± 1 %.
5 , the load power factor : the ability to characterize the capacitive load inverter with inductive load or . In the sine condition, the load power factor of 0.7 to 0.9 ( hysteresis ) , the rating is 0.9 .
6, rated output current : Indicates the inverter within the specified range of the rated output power factor of the load current . Some inverter products given is rated output capacity , the unit in VA or KVA said . The rated capacity of the inverter when the output power factor of 1 ( ie, purely resistive load ) , the rated output voltage of the rated output current of the product.
7 , rated output efficiency: The efficiency of the inverter under specified operating conditions , the output power to input power ratio , in%. Inverter efficiency at rated output capacity for full load efficiency of 10% at rated output capacity efficiency at low load efficiency.
8 , Protection: over-voltage protection : No voltage stabilization measures for the inverter output over-voltage protection measures due to the negative output cut from overvoltage damage.
Overcurrent protection : inverter over-current protection , should be able to ensure that a short circuit in the load current exceeds the allowable value or action from time to time , so from inrush current damage.
9 , starting characteristics : characterizing the performance of the inverter starting with a load capacity and dynamic work. The inverter should ensure reliable starting at rated load .
10 , the noise : the transformer power electronic device , the filter inductor , electromagnetic switches and other components are the fan noise is generated . Normal operation of the inverter , the noise should not exceed 80dB, small inverter noise should not exceed 65dB.
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2014年5月28日星期三
2014年5月18日星期日
5kW off-grid PV inverter control strategy
SPWM control technology in a wide range of inverter circuit , we use a closed-loop PID control with a combination of negative feedback control of digital control strategy.
Generating a control pulse
This article is based on TI 's main chip , F2812 12 volt inverter There are two event manager EVA and EVB, each of which can generate a pulse output 8-channel , in which three pairs of complementary signal output from the full compare unit , each pair of complementary signals delay from the corresponding dead time timer generated , the event manager using the internal timer , and comparison means generates a corresponding pulse. Man in a pair of complementary output SPWM pulse signal and PWM signal output by one independent EVA, respectively Boost boost control circuit and an inverter circuit .
2 Output frequency calculations
SPWM inverter output frequency of the pulse signal is 50Hz, points SPWM output waveform of each sine wave cycle depends on the carrier frequency and the target output sine wave frequency SPWM pulse waves. As for the carrier frequency SPWM 18kHz, the frequency of the sine wave to be 220v inverters outputted respectively 50Hz, sine table needed for the point N
3 closed-loop negative feedback control
DSP2812 time detection output voltage input , the current value fed to the internal DSP , after the PI regulator to change the parameters associated register , controls the waveform of the drive pulses to achieve real-time closed-loop control , the control system block diagram shown in Figure 6, the system uses two closed loop negative feedback , depending on the feedback signal, the output of real-time adjustment , the output is stable. In addition, when the output current signal suddenly increases to exceed the maximum allowable current when off the PWM output to protect the inverter device from damage.
Generating a control pulse
This article is based on TI 's main chip , F2812 12 volt inverter There are two event manager EVA and EVB, each of which can generate a pulse output 8-channel , in which three pairs of complementary signal output from the full compare unit , each pair of complementary signals delay from the corresponding dead time timer generated , the event manager using the internal timer , and comparison means generates a corresponding pulse. Man in a pair of complementary output SPWM pulse signal and PWM signal output by one independent EVA, respectively Boost boost control circuit and an inverter circuit .
2 Output frequency calculations
SPWM inverter output frequency of the pulse signal is 50Hz, points SPWM output waveform of each sine wave cycle depends on the carrier frequency and the target output sine wave frequency SPWM pulse waves. As for the carrier frequency SPWM 18kHz, the frequency of the sine wave to be 220v inverters outputted respectively 50Hz, sine table needed for the point N
3 closed-loop negative feedback control
DSP2812 time detection output voltage input , the current value fed to the internal DSP , after the PI regulator to change the parameters associated register , controls the waveform of the drive pulses to achieve real-time closed-loop control , the control system block diagram shown in Figure 6, the system uses two closed loop negative feedback , depending on the feedback signal, the output of real-time adjustment , the output is stable. In addition, when the output current signal suddenly increases to exceed the maximum allowable current when off the PWM output to protect the inverter device from damage.
2014年5月6日星期二
Functional skills
An additional output voltage
Within the limitations of the input DC voltage shake rule promised , it revealed that the performance of the extra voltage inverter should be able to output . Additional output voltage Solar power inverters accuracy is unchanged following general rules:
( 1 ) In the steady state 12 volt power inverters operation, the voltage should be a limit to shake limitations , such as its deviation does not exceed ± 3% or ± 5% extra value .
( 2 ) the load gradient ( extra load 0% → 50% → 100%) or other troubling elements under dynamic conditions affect the output voltage deviation should not exceed ± 8% additional value or ± 10%.
2 , refused to accept 24 volt power inverters the value of the output voltage
Under the premise of normal tasks , three-phase voltage value of the inverter output satisfied (the weight of the positive-sequence reverse -weight ratio ) should not exceed the value of a rule , the general performance disclosed in% , such as 5 % or 8 %.
3, the output voltage waveform degrees off true
When the inverter output voltage is sinusoidal , the maximum waveform should rule out the promise of truth degrees ( or harmonic content ) . Mortal with a total output voltage waveform revealed truth degrees out performance , and its value should not exceed 5% ( single phase output promised 10% ) .
4 , an additional output frequency
Inverter output frequency of the AC voltage should be a relatively constant value , for the mortal frequency 50Hz. Under the premise of their normal tasks tend to be within ± 1 %.
5 , the load power factor
Inverter with rational characterization to load or capacitive loads. Under the premise of a sine wave , the load power factor of 0.7 to 0.9 ( hysteresis ) , the additional value of 0.9 .
6 , the additional output 220 volt inverter current ( or additional output capacity )
Revealed that the performance of the extra load power factor output current limitation rules inverter . Some of the inverter is given by the product of the additional output capacity , the unit in VA or KVA disclose performance. Additional capacity of the inverter when the output power factor of 1 ( ie, purely resistive load ) , the additional output voltage is the product of the additional output current .
7 , additional output efficiency
The efficiency of the inverter under the premise of the rule task , the output power to input power ratio, % disclose performance. Additional inverter output capacity efficiency under full load efficiency is at 10% efficiency of the output capacitor, the additional low -load efficiency .
8 , Maintenance
( 1 ) Over Voltage Maintenance: About the same way no voltage inverter , output over-voltage protection should be ways to cut from the negative output over-voltage damage.
( 2 ) Over-current Maintenance: overcurrent inverter maintenance , should be able to guarantee the onset of a short circuit in the load or the current value of real-time initiatives beyond the agreed time , so from inrush current damage .
9 , starting characteristics
Characterization of the inverter can start with functional and dynamic load tasks. The inverter should assure reliable starter in the extra load .
10 , the noise
Power electronic devices in the transformer, the filter inductor , the electromagnetic switch and other components are the fan noise will occur. Normal operation of the inverter , the noise should not exceed 80dB, small inverter noise should not exceed 65dB.
Within the limitations of the input DC voltage shake rule promised , it revealed that the performance of the extra voltage inverter should be able to output . Additional output voltage Solar power inverters accuracy is unchanged following general rules:
( 1 ) In the steady state 12 volt power inverters operation, the voltage should be a limit to shake limitations , such as its deviation does not exceed ± 3% or ± 5% extra value .
( 2 ) the load gradient ( extra load 0% → 50% → 100%) or other troubling elements under dynamic conditions affect the output voltage deviation should not exceed ± 8% additional value or ± 10%.
2 , refused to accept 24 volt power inverters the value of the output voltage
Under the premise of normal tasks , three-phase voltage value of the inverter output satisfied (the weight of the positive-sequence reverse -weight ratio ) should not exceed the value of a rule , the general performance disclosed in% , such as 5 % or 8 %.
3, the output voltage waveform degrees off true
When the inverter output voltage is sinusoidal , the maximum waveform should rule out the promise of truth degrees ( or harmonic content ) . Mortal with a total output voltage waveform revealed truth degrees out performance , and its value should not exceed 5% ( single phase output promised 10% ) .
4 , an additional output frequency
Inverter output frequency of the AC voltage should be a relatively constant value , for the mortal frequency 50Hz. Under the premise of their normal tasks tend to be within ± 1 %.
5 , the load power factor
Inverter with rational characterization to load or capacitive loads. Under the premise of a sine wave , the load power factor of 0.7 to 0.9 ( hysteresis ) , the additional value of 0.9 .
6 , the additional output 220 volt inverter current ( or additional output capacity )
Revealed that the performance of the extra load power factor output current limitation rules inverter . Some of the inverter is given by the product of the additional output capacity , the unit in VA or KVA disclose performance. Additional capacity of the inverter when the output power factor of 1 ( ie, purely resistive load ) , the additional output voltage is the product of the additional output current .
7 , additional output efficiency
The efficiency of the inverter under the premise of the rule task , the output power to input power ratio, % disclose performance. Additional inverter output capacity efficiency under full load efficiency is at 10% efficiency of the output capacitor, the additional low -load efficiency .
8 , Maintenance
( 1 ) Over Voltage Maintenance: About the same way no voltage inverter , output over-voltage protection should be ways to cut from the negative output over-voltage damage.
( 2 ) Over-current Maintenance: overcurrent inverter maintenance , should be able to guarantee the onset of a short circuit in the load or the current value of real-time initiatives beyond the agreed time , so from inrush current damage .
9 , starting characteristics
Characterization of the inverter can start with functional and dynamic load tasks. The inverter should assure reliable starter in the extra load .
10 , the noise
Power electronic devices in the transformer, the filter inductor , the electromagnetic switch and other components are the fan noise will occur. Normal operation of the inverter , the noise should not exceed 80dB, small inverter noise should not exceed 65dB.
2014年5月4日星期日
Simple production of the inverter
Since the start of the instantaneous current larger TV, you must consider the inverter waveforms, power margin, power factor, and so the production of soft-start control, so do it yourself
12v power inverter requires professional knowledge and skills, more difficult, if not road easily damaged by electrical or inverter itself. Besides, 12V motorcycle battery capacity is 7 or 9 Ann Ann, separate 100W bulb for 40 minutes on the use of a 21-inch color TV also does not take 40 minutes, if it is an old battery, charging waited a long time, not a few comes to an end. The best solution is the choice of 300W UPS External around 50 Ah car battery.
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