WO2010121523A1

WO2010121523A1 - Full load testing method of low power consumption for converter

Info

Publication number: WO2010121523A1
Application number: PCT/CN2010/071793
Authority: WO
Inventors: 李兴; 李旷; 左强; 郭自勇; 徐颖; 付国良; 丁雅丽
Original assignee: 荣信电力电子股份有限公司
Priority date: 2009-04-25
Filing date: 2010-04-15
Publication date: 2010-10-28
Also published as: CN101539603A

Abstract

A full load testing method of low power consumption for a converter includes follow steps: 1) connecting an input end of the converter to be tested with a power grid, and connecting an output end of the converter to be tested to the input end of the converter via a reactor (L), 2) controlling active power P outputted from the converter by adjusting an effective value I of current outputted from the converter to be tested and power factor cosϕ, 3) judging whether the converter to be tested has passed the load test with the set output power P by monitoring whether various operating indicators of the converter to be tested are normal or not after operating for a stated time with the active power P.

Description

Micro-power converter full-load test method

The invention relates to a converter test method, in particular to a micro-power converter full load test method. Background technique

A converter is a conversion device that converts electrical energy of one current into electrical energy of another current. The load test of the converter refers to the test of the load carrying capacity of the converter. That is, the magnitude of the output current of the converter under the rated output voltage directly reflects the load transfer capacity of the converter. The test requires two necessary conditions: power supply conditions and load conditions.

At present, there are two main methods for performing full load converter test:

1) Energy consumption test plan

The tested converter is connected to a motor, which is mechanically connected to the generator. The output of the generator is directly connected to the resistive load, or connected to the resistive load through a converter (such as a rectifier), and the power output of the generator is consumed. Sexual load. It is characterized by the fact that these accessible resistive loads consume large amounts of electrical energy during full load testing.

2) Back-to-back motor unit test plan

The patent number is ZL200820069333. X. The Chinese utility model patent entitled "Energy feedback device based on power unit series high-voltage frequency converter" discloses an energy feedback inverter, which satisfies the four-quadrant operation of the power unit series high-voltage inverter. Requirements, and has a very good energy saving effect. The device flows the energy generated by the generator power generation operation through a single-phase H-type bridge inverter circuit, a DC bus, and a PWM rectifier and a filter reactor operating in an inverter state, and the electric energy flows from the motor to the power grid through the converter.

See Figure 1. The device used in this method is a tested converter, a companion converter and first and second motors Ml,

M2, the electric energy from the power grid is transmitted to the tested converter through the first transformer T1, the output of the tested converter is connected to the first motor M1, and the first motor M1 is connected to the second motor M2 through the coupling, the second motor The output of the M2 is connected to the test converter, and the output power of the converter is returned to the same grid or different grid via the second transformer T2. The advantages of this solution are: It can verify the control ability of the converter to the motor, that is, the speed regulation performance of the converter, and the converter can be tested at different frequencies. The disadvantage is that the equipment investment is large and the cost is high. It is necessary to have two motors and accompanying converters with the same power as the converter under test.

Due to the limitations of power supply capacity and other conditions, for high-power converters, some manufacturers only perform no-load or light-load tests, and can only perform field load tests at the application site. The method of being able to perform a full load test of the converter has not been reported.

Summary of the invention

The technical problem to be solved by the present invention is to provide a simple structure and a manufacturing cost, in view of the limitation of the power capacity and the like in the prior art, and the limitation of the field load test can be performed only at the application site. A low power, low energy loss, a micropower converter full load test method that does not use an electric motor.

To achieve the above object, the present invention is achieved by the following technical solutions:

A micropower converter full load test method of the present invention comprises the following steps:

1) connecting the input end of the tested converter to the power grid, and the output end of the tested converter is connected back to the converter input end via the reactor;

2) Control the active power of the converter output by adjusting the magnitude and power factor of the RMS value of the output current of the converter (Χ^Φ)

3) Run the above-mentioned active power for a specified period of time. By monitoring whether the various operating indicators of the tested converter are normal, determine whether the tested converter passes the load test under the specified output power.

The control determines the active value of the output current of the converter and the power factor (Χ^Φ to control the active power output of the converter / ^ specifically:

Calculate the rms value of the output current of the converter according to the formula P = V3f// *C0SO and the grid line voltage; compare the detected actual output current RMS value with the given value of the RMS value of the above output current, and pass PI Or the PID adjustment changes the output pulse width modulation ratio of the tested converter, so that the output current rms value / is equal to the current rms value given value / *, the phase is the same, and the tested converter output power and the specified output are realized. The power is equal.

The various operational indicators of the tested converter include: temperature rise of the internal transformer of the converter, temperature rise of the semiconductor power device, temperature rise of the cable and the busbar, stability of the control control system under full load conditions, The efficiency of the frequency converter and the effectiveness of the protection system.

The output voltage of the tested converter is higher than the grid voltage.

The fundamental frequency of the output current of the tested converter is equal to the grid frequency; the phase sequence of the output current of the converter is the same as the corresponding input phase sequence; the phase angle of the fundamental current of the converter output current and the phase of the grid voltage The angle is the same.

The converter is a non-four-quadrant two-level rectification, two-level inverter structure, a non-four-quadrant two-level rectification, a three-level inverter structure, and a four-quadrant three-level rectification, three-level inverter structure.

The converter is a non-four-quadrant H-bridge power unit series high-voltage converter, the rectification part of the power unit is two-level, the inverter part is a two-level structure; or the converter is a non-four-quadrant H-bridge power unit series high-voltage converter, the rectification part of the power unit is two-level, the inverter part is a three-level structure; or the converter is a four-quadrant H-bridge power unit series high-voltage converter The rectifying part is of two levels, and the inverter part is of two-level structure; or the converter is a four-quadrant H-bridge power unit series high-voltage converter, the rectifying part is three-level, and the inverting part is Three-level structure.

The advantages of the present invention over the prior art are:

1. Applying the method of the invention to the full load test of the converter, so that the power grid only needs to supplement the power loss of the tested converter, and usually only accounts for a few percent of the rated power of the converter under test, thus being limited. Under the condition of power grid capacity, it is possible to test the converter load far exceeding the capacity of the power grid. It overcomes the limitation that the full load test of the converter can only be carried out when the power supply capacity is sufficient. The energy comes in from the power grid and passes the test. The flow device, back to the grid, requires only a small amount of energy to be added, and is a complete energy-saving test method.

2. The method of the invention does not require the accompanying converter and the test motor, which greatly simplifies the structure of the converter full load test, and also greatly saves the test cost, the investment in the test equipment is small, and the running cost is low.

3. To save energy, the power consumed by the test is only 2-3% of the power consumed by the traditional converter full load test.

4. The method of the invention can be applied to the full load test of various types of converters, and has wide adaptability.

DRAWINGS

1 is a schematic diagram showing the structure of a back-to-back motor unit test plan in the background art;

2 is a schematic structural view of the present invention;

Figure 3 is a schematic diagram of energy transfer of the present invention;

4 is a schematic structural view of a non-four-quadrant two-level converter;

Figure 5 is a schematic structural view of a four-quadrant two-level converter;

6 is a schematic structural view of a non-four-quadrant three-level converter;

7 is a schematic structural view of a four-quadrant three-level rectification and three-level inverter converter;

8 is a schematic structural view of a four-quadrant power unit series high-voltage converter;

Figure 9 is a schematic diagram showing the structure of a four-quadrant power unit series high-voltage converter (the rectification part of the power unit is two-level, and the inverter part is two-level);

Figure 10 is a schematic diagram showing the structure of a non-four-quadrant power unit series high-voltage converter (the rectification part of the power unit is two-level, and the inverter part is three-level);

Figure 11 is a schematic structural view of a four-quadrant power unit series high-voltage converter (three-level rectification part and three-level inverter part);

Figure 12 is a single line diagram of the principle of the full-load test method for a micro-power converter;

Figure 13 is a schematic diagram of a single-phase equivalent circuit of a micro-power converter full load test method;

Figure 14 is a single-phase phasor diagram of a micro-power converter full load test method; Figure 15 is a block diagram of the control scheme for the micro-power converter full load test method.

detailed description

1) connecting the input end of the tested converter to the power grid, and the output end of the converter is connected back to the converter input via the reactor;

2) Control the active power of the converter output by adjusting the converter output current rms/size and power factor (Χ^Φ)

The test method of the present invention is explained in the following steps:

1) Connect the input of the tested converter to the grid, and the output of the converter is connected back to the converter input via the reactor. As shown in Figure 2, as shown in Figure 3, the input of the converter will be tested. Connected to the grid via transformer T, the output of the converter is connected to the input via reactor L; the energy lost is supplemented by the grid. The role of reactor L is to match the output of the converter to the grid.

2) Control the active power of the converter output by adjusting the magnitude and power factor of the RMS value of the output current of the converter (Χ^Φ ^

According to the formula P

And the grid line voltage is used to obtain a given value of the converter output current RMS value; the detected actual output current RMS value is compared with the given value of the output current RMS value, and the subject variable current is changed by PI or PID adjustment The output pulse width modulation ratio of the device makes the output current RMS/equal to the given value of the current RMS/*, and the phase is the same, and the output power of the tested converter is equal to the specified output power.

The principle of the test method is shown in Figure 12. The current output of the converter is tested. In phase with the grid voltage ^, that is, the converter delivers pure active power to the grid (power factor is 1),

(1)

(2)

P..+P, p + p (3)

P = P, (4)

₁ is the grid input current for the tested converter, and i _n is the output of the tested converter.

For the tested converter current loss, ^ is the grid power, the input power of the tested converter, the output power of the tested converter, L, is the power loss of the converter under test.

The input power (current) of the converter is provided by the grid power (current) and the output power (current) of the converter under test, that is, the grid only needs to provide the loss energy of the converter under test. Therefore, by controlling the magnitude of the output current of the tested converter, the input power and output power of the tested converter can be controlled.

When the unit power factor is C0SO=l, and only the fundamental power is considered,

P _m =^UI _m (5)

P _o = UI ₀ (6)

In the above formula, it is the grid line voltage, /„ is the input phase current rms value for the converter, and / is the converter output phase current effective value.

Full load test efficiency is

= P _a iP _m (7)

Conditions to be met by the test method:

The converter should have the ability to have its output voltage slightly higher or higher than the grid voltage; The output fundamental frequency of the converter should be equal to the grid frequency;

The output phase sequence of the converter is the same as the corresponding input phase sequence;

The phase angle of the fundamental current of the converter output current is the same as the phase angle of the grid voltage;

Controlling the output power of the converter by controlling the magnitude of the output current of the converter;

The capacity of the grid is greater than the power loss of the converter under test.

The single-phase equivalent circuit diagram of the test method is shown in Figure 13, and the phasor diagram is shown in Figure 14;

In Figure 13 and Figure 14, the converter under test is equivalent to a voltage source, the grid voltage is , and the output current of the converter is controlled. In phase with the grid voltage, the voltage drop across the reactor is jQjLi. .

Active power flows from the converter to the grid, the size is

P = - -sin δ

Wherein, the phase converter is equivalent to the phase angle of the voltage and the grid voltage, and is the effective value of the grid line voltage, which is the mode of the grid voltage, the mode of the voltage source, and the equivalent inductance of the converter. /. Outputs the phase current rms value for the converter.

In the above formula, the power of the single-phase circuit, the total output power of the tested converter is:

P _all = 3P = 3U ₀ = UI _Q = P ₀ (9)

Test block control block diagram shown in Figure 15, for the converter output power command, according to formula (6) and grid line voltage to obtain the converter output current given rms; the synchronization circuit can get the same phase with the grid voltage The sinusoidal synchronizing signal can then calculate the current given instantaneous values of the three currents representing the three phase currents of the converter output in real time; the three current given instantaneous values are compared with the instantaneous feedback values of the corresponding phases of the tested converter The current error is obtained, and the current error is modulated by the PWM regulator into a PWM control pulse signal by the current regulator, and the output current of the converter is controlled by controlling the amplitude of the output voltage of the converter. The purpose of controlling the output power of the converter is achieved.

3) Run for the specified time under the above-mentioned active power, and judge whether the tested converter passes the load test under the specified output power P by monitoring whether the various operating indicators of the tested converter are normal.

Different types of converters have different running times during full load test, depending on the standard or user specific requirements of the converter. The various operating indicators of the monitored converter refer to the internal transformer temperature rise of the converter. , temperature rise of semiconductor power devices, temperature rise of cables and busbars, stability of control system under full load conditions, efficiency of frequency converters, and effectiveness of protection systems; The internal transformer temperature rise, the temperature rise of the semiconductor power device, and the temperature rise of the cable and busbar do not exceed the limits of the converter design, or the control control system works well under full load conditions, and the efficiency of the inverter is not The reduction and protection system are effective, etc., indicating that the tested converter passed the full load test and reached the performance requirements of the design requirements. Otherwise, if one of the measured indicators exceeds the design limit, it means that the tested converter failed to pass the full load test and needs to be rectified.

The test converter to which this method can be applied shall have the following structure:

Non-four quadrant two-level structure. As shown in Figure 4, the rectifier side of the converter is the input transformer T, the diode D _w , the non-four-quadrant structure, the capacitor constitutes the DC filter circuit, and the inverter side is the fully-controlled power semiconductor switching device ^^, V ^, composed of a two-level output structure. Four-quadrant two-level structure. As shown in FIG. 5, the rectifier side of the tested converter is a four-quadrant structure composed of fully-controlled power semiconductor switching devices V ₂ - ₂ , V ₃ - ₂ , V ₄ - ₂ , V ₅ - ₂ , and V ₆ - ₂ . The capacitor d- ₂ constitutes a DC filter circuit, and the inverter side is a fully controlled power semiconductor switching device V ₇ - ₂ , V ₈ - ₂ , V ₉ - ₂ , V ₁₀ _ ₂ , V _u — ₂ , V ₁₂ - ₂ A two-level output structure.

Non-four quadrant three-level structure. As shown in FIG. 6, the rectifier side of the tested converter is a non-four-quadrant structure composed of an input transformer T, diodes D ₂ - ₃ , D ₃ - ₃ , D ₄ - ₃ , D ₅ - ₃ , and D ₆ - ₃ , The capacitors d- ₃ and C ₂ - ₃ form a DC filter circuit, and the inverter side is a fully-controlled power semiconductor switching device V ₂ - ₃ , V ₃ - ₃ , V ₄ - ₃ , V ₅ - ₃ , V ₆ - ₃ , V ₇ - ₃ , v ₈ - ₃ , v ₉ - ₃ , ν _ω - ₃ , V _u - ₃ , v ₁₂ - ₃ , and diodes D ₇ - ₃ , D ₈ - ₃ , D ₉ - ₃ , DD _u - ₃ , D ₁₂ - ₃ three-level output structure.

Four-quadrant three-level rectification, three-level inverter structure. As shown in FIG. 7, the rectifier side of the tested converter is a fully-controlled power semiconductor switching device ^ ₅ , V ₂ — ₅ , V ₃ — ₅ , V ₄ —, V ₅ —, V ₆ —, V ₇ — ₅ , V ₈ — ₅ , V ₉ — ₅ , V ₁₍₎ — ₅ , V _U — ₅ , V ₁₂ — ₅ , and diodes D ₂ - ₅ , D ₃ - ₅ , D ₄ - ₅ , D ₅ - ₅ , A four-quadrant structure consisting of D ₆ - ₅ , capacitors d- ₅ , C ₂ - ₅ form a DC filter circuit, and the inverter side is a fully-controlled power semiconductor switching device V ₁₃ - ₅ , V ₁₄ - ₅ , V ₁₅ - ₅ , V ₁₆ - ₅ , V ₁₇ - ₅ , V ₁₈ - ₅ , V ₁₉ - ₅ , V ₂ . - ₅ , V ₂₁ - ₅ , V ₂₂ - ₅ ,

A three-level output structure consisting of V ₂₃ - ₅ , V ₂₄ - ₅ , and diodes D ₇ - ₅ , D ₈ - ₅ , D ₉ - ₅ , D ₁₀ - ₅ , D _U - ₅ , and D ₁₂ - ₅ .

The tested converter may also be a non-four quadrant H-bridge power unit series structure as shown in FIG.

The tested converter can also be a four-quadrant power H-bridge unit series high-voltage converter as shown in Fig. 9. The rectification part of the power unit is two-level, and the inverter part is a two-level structure.

The tested converter may also be a non-four-quadrant H-bridge power unit series high-voltage converter as shown in FIG. 10, the rectifying portion of the power unit is two-level, and the inverter portion is a three-level structure.

The tested converter can also be a four-quadrant power unit series high-voltage converter as shown in Fig. 11, the rectification part is three-level, and the inverter part is three-level structure.

Claims

Claim

1. A micropower converter full load test method, comprising the steps of:

2) Control the active power of the converter output by adjusting the magnitude and power factor (Χ^ Φ) of the output current RMS of the tested converter.

3) Run for the specified time under the above-mentioned active power, and judge whether the tested converter passes the load test under the specified output power by monitoring whether the various operating indicators of the tested converter are normal.

2. The micropower converter full load test method according to claim 1, wherein:

The control determines the active value of the output current I of the converter and the power factor (Χ^ Φ to control the active power output of the converter / ^ specifically:

The given value of the RMS value of the converter output current is obtained according to the formula P = V3f / / * C0S O and the grid line voltage; the detected actual output current RMS value / compared with the given value of the above output current RMS value, The output pulse width modulation ratio of the tested converter is changed by PI or PID adjustment, so that the output current RMS value/equal to the current rms value/* is the same, the phase is the same, and the output power of the tested converter is specified. The output power is equal.

3. The micro-power converter full load test method according to claim 1, wherein: the operating indexes of the tested converter include: converter internal transformer temperature rise, semiconductor power device The temperature rise, the temperature rise of the cable and busbar, the stability of the control system under full load conditions, the efficiency of the frequency converter and the effectiveness of the protection system.

4. The micropower converter full load test method according to claim 1, wherein: the output voltage of the tested converter is higher than a grid voltage.

5. The micropower converter full load test method according to claim 1, wherein: the fundamental frequency of the output current of the tested converter is equal to the grid frequency; and the output current of the converter The phase sequence is the same as the corresponding input phase sequence; the phase angle of the fundamental current of the converter output current is the same as the phase angle of the grid voltage.

6. The micropower converter full load test method according to claim 1, wherein: said converter is a non-four-quadrant two-level rectification, two-level inverter structure, and not four quadrants. Level rectification, three-level inverter structure and four-quadrant three-level rectification, three-level inverter structure.

7. The micro-power converter full load test method according to claim 1, wherein: said converter is a non-four-quadrant H-bridge power unit series high-voltage converter, and the power unit is rectified. The part is two-level, and the inverter part is a two-level structure; or the converter is a non-four-quadrant H-bridge power unit series high-voltage converter, and the rectification part of the power unit is two-level, the inverter part a three-level structure; or the converter is a four-quadrant H-bridge power unit series high-voltage converter, the rectification portion is two-level, the inverter portion is a two-level structure; or the converter is Four quadrant

The H-bridge power unit series high-voltage converter has a three-level rectification portion and a three-level inverter portion.