KR102679487B1 - AC-DC converter employing load sharing with parrallel structure - Google Patents

Abstract

The embodiment relates to an AC-DC converter with a load sharing parallel structure.
Specifically, these AC-DC converters are equipped with multiple power control modules in a module format and installed in parallel, so that when one or more of the multiple power control modules fails, use is limited to only the failed module. The normal module maintains the operability of the operating equipment in use with minimal output.
Therefore, if a failure occurs in a converter used in a special vehicle, the AC input is maintained and the operating equipment continues to operate, thereby maintaining the operability of the operating equipment in use.

Description

AC-DC converter employing load sharing with parallel structure}

The content disclosed in this specification relates to an AC-DC converter for special vehicles. More specifically, while operating special vehicles such as electric vehicles and refrigerated trucks, AC power is input through a single-phase alternator and converted to DC power to be used as operating equipment. It is about a converter that supplies .

Unless otherwise indicated herein, the material described in this section is not prior art to the claims of this application, and is not admitted to be prior art by inclusion in this section.

In general, interest in the power quality of AC-DC converters for special vehicles is increasing due to the influence of electric vehicle technology development and environmental warming suppression.

AC-DC converters for special vehicles are used in electric vehicles and refrigerated trucks, etc., and receive AC power through a single-phase alternator, convert it into DC power, and supply it to operating equipment. For reference, the operating equipment includes batteries and several fans. It largely consists of interleaved PFC (Power Factor Correction), ZVS-PSFB (Zero Voltage Switching-Phase Shifted Full Bridge), and synchronous rectifier (SR: Synchronous Rectifier).

Interleaved PFC receives AC power through a single-phase alternator, corrects the power factor, converts it into DC power through a rectifier and power switching element, and provides it as auxiliary DC power connected in parallel. The ZVS-PSFB is capable of implementing ZVS with reduced switching losses using a phase-shifted full-bridge DC-DC converter technique.

In these converters, abnormalities in interleaved PFC, ZVS-PSFB, and synchronous rectifiers are mostly caused by failure of power switching devices such as IGBT and SiC.

Failure of switching elements can be broadly divided into short circuit failure and open circuit failure.

When a short circuit failure occurs, the power is usually cut off by a protection circuit such as a breaker or fuse, but if this is not the case, the switching element may be damaged or serious damage may be caused to surrounding elements.

On the other hand, if an open circuit failure occurs, the system does not immediately stop but continues to operate with reduced performance. At this time, the current contains many harmonic components, each phase causes imbalance, and the generated DC terminal voltage causes fluctuation of the system frequency component. If this operation continues, malfunctions of other elements may lead to secondary failures in the converter system, load, or system due to unstable operation.

Therefore, when a failure of a switching element occurs in a converter system, the cause of the failure must be quickly determined and resolved. However, finding the cause takes a lot of time and money, and as the system becomes more complex, the task becomes more difficult. If the converter breaks down while operating the equipment, the environment may become difficult to operate.

The prior art in this background is the following literature.

Document 1 Korean Patent No. 10-1235182 Document 2 Korean Patent No. 10-1796741 Document 3 Korean Patent No. 10-2011378 Document 4 Korean Patent No. 10-1969391

The disclosed content seeks to provide an AC-DC converter with a load sharing parallel structure that can maintain the operability of the operating equipment in use by continuing to operate the operating equipment when a failure occurs in the converter used in a special vehicle.

The AC-DC converter with a load sharing parallel structure according to the embodiment,

The power control module that converts AC power to DC power is composed of three 1kW power and installed in parallel. If one or more of the configured power control modules is broken, use is restricted to only the failed module. The normal module has the advantage of improving the equipment operation rate by maintaining the operability of the operating equipment with minimal output.

According to embodiments, when a failure occurs in a converter used in a special vehicle, the operational equipment is continuously operated to maintain the operability of the operational equipment in use. If there is no countermeasure for the failure of the AC-DC converter, it becomes impossible to operate the equipment in a failure situation. However, by overcoming this condition, it is possible to provide a converter for special vehicles that maintains AC input.

1 is a diagram conceptually illustrating an AC-DC converter with a load sharing parallel structure according to an embodiment.
FIG. 2 is a diagram conceptually illustrating the configuration of an AC-DC converter with a load sharing parallel structure according to an embodiment.
FIG. 3 is a diagram conceptually illustrating the operation of an AC-DC converter with a load sharing parallel structure according to an embodiment.
Figure 4 is a diagram for specifically explaining the operation of an AC-DC converter with a load sharing parallel structure according to an embodiment.
Figure 5 is a diagram for explaining the operation of the AC-DC converter of the load sharing parallel structure according to this embodiment.
Figure 6 is a block diagram showing the configuration of an AC-DC converter with a load sharing parallel structure according to an embodiment.
Figure 7 is a flow chart sequentially showing the operation of an AC-DC converter with a load sharing parallel structure according to an embodiment.

Figure 1 is a diagram to conceptually explain an AC-DC converter with a load sharing parallel structure according to an embodiment.

As shown in FIG. 1, the AC-DC converter 100 of a load sharing parallel structure according to an embodiment converts the 220V AC output voltage of a special-purpose vehicle alternator into 28V DC voltage and stably supplies it to various electrical loads. It is a device that

When a converter failure occurs in a special vehicle, one embodiment converts AC power into DC power and supplies it under these operating conditions, and also supplies it to the operating equipment at a minimum output to effectively maintain operability.

In other words, if there is no countermeasure for the converter failure situation, the equipment cannot be operated in the failure situation. However, by overcoming this condition, AC input can be maintained.

This AC-DC converter 100 first receives AC power through a single-phase alternator, converts it into DC power, and supplies it to the load, as before. The load can be selected through CAN communication under the control of the upper controller, and power can be supplied through the transfer unit only to the selected load. The load includes a battery, fan 1, and fan 2 as operating equipment, and the administrator can select and operate one or more of them.

In this state, one embodiment first provides a plurality of power control modules and shares DC power from them to supply the load. For example, when using three power control modules, one power control module supplies 1kw, for a total of 3kw to the load.

If one or more of multiple power control modules is broken, use of the failed module is limited. The normal module continuously supplies DC power to the load. In other words, in the case above, if one module breaks down, a total of 2kw is supplied from the two power control modules.

Therefore, when a failure occurs in a converter used in a special vehicle, the AC input is maintained to continue operating the operating equipment to maintain the operability of the operating equipment in use. The specific configuration is as shown in Figure 2.

In more detail, one embodiment is made as follows.

First, control circuit design using MCU (Micro Controller Unit) and PWM (Pulse Width Modulation) switching circuit design using power devices, PFC (Power Factor Correction) bidirectional structure for high efficiency and ZVS-PSFB (Zero Voltage Switching-Phase Shifted) It was designed as a full bridge.

The MCU (Micro Controller Unit) on the main control board of the main components manages the power supply set assembly temperature, voltage, and load characteristics and controls peripheral devices. It checks the status of microprocessor peripheral devices and transmits and receives sensor signal information, and the design application model uses ST's STM32F, a 32-bit multi-function MCU.

In addition, the software is designed according to SDP (Software Development Plan) standards, and the internal communication circuit is advantageous for CAN (Controller Area Network) communication data transmission and SCI (Serial Communication Interface) communication, which has a simple circuit, is added for error checking and real-time update. It was implemented to make it possible. Sensor detection circuit Applying voltage, current, and temperature sensors to allow the processor to recognize, peripheral circuits such as OP-AMP and PHOTO-COUPLER are used to amplify and attenuate the converted value that the processor can recognize, and to detect the sensor value. The sensor detection circuit and conversion function are implemented, and the influence of surrounding noise is minimized by applying A/D (Analog to Digital) and LPF (Low Pass Filter) to the sensor detection circuit. The digital I/O circuit plays the role of converting the input and output signal levels of the processor, peripheral devices, and signals, and prevents signal malfunction by applying full up and full down resistance elements depending on the signal characteristics to prevent the input and output signals from floating. It was designed to do so.

In addition, the power control board uses a PFC circuit controlled by signals from the control unit at the input terminal, and the power factor correction circuit is designed with an interleaved structure. The power control board consists of three identical power control modules using a ZVS-PSFB (Zero Voltage Switching-Phase Shifted Full Bridge) circuit and an inductor for insulation, enabling an output of at least 1.0 kW per unit module. The inductor is composed of a transformer and filter with an internal insulation structure, and an insulation structure design considering safety was applied. The circuit receives 80~265 ACV voltage and rectifies it to DC through a circuit and FBO40-12N bridge diode, and NTC CL-40 protects the inrush current.

Figure 2 is a block diagram to conceptually explain the configuration of an AC-DC converter with a load sharing parallel structure according to an embodiment.

As shown in FIG. 2, the AC-DC converter 100 according to one embodiment largely includes a plurality of power control modules 110, a driver 120, and a control unit 130.

As before, the plurality of power control modules 110 have a bidirectional bridgeless PFC, ZVS-PSFB, and synchronous rectifier.

The driver 120 has one first gate driver that commonly drives the power switching elements of the bidirectional bridgeless PFC of the plurality of power control modules 110. In addition, each of the power control modules 110 has a plurality of second gate drivers that drive the power switching elements of each ZVS-PSFB and the synchronous rectifier.

The control unit 130 controls the first and second gate drivers of the driving unit 120 to share the DC power of the multiple power control modules 110 and supply it to the load. The supplied DC power value is detected through a sensor and compared to a set reference value, and if there is a difference, it is determined to be in an abnormal state. Therefore, the second gate driver of the fault module is controlled to turn off the power switching element of the ZVS-PSFB to block the power supply to the load. For reference, power supply to the load of the normal module is maintained.

Meanwhile, when the output power is unstable or unstable, this converter controls the power switching element of the bidirectional bridgeless PFC by varying the standard duty ratio determined for each load, thereby increasing the output current and improving stability. High temperatures can cause danger and performance deterioration of rotating machines, motors, and pumps.

For this purpose, it includes a voltage detection unit 111 that detects the voltage of the DC power supply of the plurality of power control modules and a temperature detection unit 112 that detects the external temperature surrounding the voltage detection unit 111.

In addition, the control unit 130 drives the power switching element of the bidirectional bridgeless PFC by varying the reference duty ratio according to the output voltage of the power control modules and the surrounding external air temperature.

First, when the control unit 130 cuts off the power supply to the load of the abnormal power control module, it detects the voltage of the output power of the normal power control module through the voltage detection unit 111.

The sensed voltage value is compared with a set reference value, and if the compared voltage value is less than or equal to the reference value as a result of the comparison, the surrounding outdoor temperature is detected through the temperature sensing unit 112.

When the detected outside temperature is -50℃ to 0℃, the standard duty ratio determined by the number of loads is increased by 30%, and when the outside temperature is above 0℃ and below 20℃, the standard duty ratio is increased by 20%, and between 20℃ and below 50℃ Until then, the standard duty ratio is increased by 10%.

Therefore, the power switching element of the bidirectional bridgeless PFC of the normal power control module is driven according to the increased reference duty ratio.

To elaborate, the bidirectional bridgeless PFC outputs higher power than the power used by the load. For reference, ZVS-PSFB is made from the power used by the load. Therefore, when supplying power to a load by reducing the number of normal power control modules, the output of the bidirectional bridgeless PFC is relatively increased to stably drive and protect the load.

The reference duty ratio is, for example, the duty ratio when supplying 1 kw as described above. The degree to which the reference duty ratio is increased is performed by setting different duty ratios for each number of loads supplying power.

For example, if the number of loads is two, the duty ratio can be increased to twice the standard duty ratio. In the case of 3, the same setting value can be used, and in the case of 5, a relatively higher setting value of 3 times can be used. The duty ratio can be added or subtracted in response to the DC power output value, such as 28V of a battery or fan.

Additionally, the control unit 130 further includes a humidity detection unit that detects the surrounding humidity of the voltage detection unit 111, and reduces the output current of the normal power control module when the humidity is higher than the first set value. If it exceeds the set value, the normal power control module is shut down. The second set value is a larger value than the first set value and may be determined depending on the capacity, load capacity, and number of the power control module.

Figure 3 is a diagram to conceptually explain the operation of an AC-DC converter with a load sharing parallel structure according to an embodiment.

As shown in FIG. 3, the AC-DC converter 100 according to one embodiment is first assumed to use, for example, three power control modules 1, 2, and 3. Multiple loads are connected to each power control module 1, 2, and 3, which can be battery, fan 1, and fan 2. One power control module supplies 1kw, and a total capacity of 3kw is shared and supplied to the load.

The specific operations are as follows.

The three power control modules 1, 2, and 3 each convert input AC power to auxiliary DC power in each bidirectional bridgeless PFC through one first gate driver under the control of the control unit 130.

In addition, the control unit 130 converts the auxiliary DC power in each ZVS-PSFB into main DC power suitable for driving the load through the second gate driver of each power control module 1, 2, and 3.

The control unit 130 isolates high-frequency components from the main DC power source through a synchronous rectifier and supplies them to the load. In this case, each power control module shares a total of 3kw, 1kw each, to stably supply it to the load.

In this state, the control unit 130 detects the supplied DC power value for each power control module 1, 2, and 3 through a sensor and compares it with a set reference value.

As a result of the above comparison, if there is a difference between the two values, it is determined to be in an abnormal state. Here, power control modules 1 and 3 are in an abnormal state.

The control unit 130 controls the second gate drivers of modules 1 and 3 in the determined abnormal state to turn off the power switching device of the ZVS-PSFB to block power supply to the load.

On the other hand, the second gate driver of module 3, which is in a normal state, is controlled to continuously keep the power switching elements of the ZVS-PSFB and the synchronous rectifier turned on to supply DC power to the load.

Therefore, when a failure occurs in a converter used in a special vehicle, the AC input is maintained to continue operating the operating equipment to maintain the operability of the operating equipment in use.

Figure 4 is a diagram for specifically explaining the operation of an AC-DC converter with a load sharing parallel structure according to an embodiment.

As shown in FIG. 4, the AC-DC converter according to one embodiment limits the use of only the failed module when one or more of the multiple power control modules 110 fails, as described above. The normal module continuously supplies DC power to the load.

The control unit 130 controls the second gate driver 50 of each power control module 110 to operate the power switching element of the ZVS-PSFB 30 by turning on the normal module and turning off the faulty module.

Specifically, the control unit 130 detects the DC power value supplied to the load for each of the plurality of power control modules 110 through a sensor and compares it with a set reference value.

As a result of the above comparison, if there is a difference between the two values, it is determined to be in an abnormal state, and each second gate driver is controlled for each module in the determined abnormal state to turn off the power switching element of the ZVS-PSFB, so that the faulty module supplies power to the load. Block.

On the other hand, the second gate driver of the module in the normal state is controlled to continuously keep the power switching device of the ZVS-PSFB and the power switching device of the synchronous rectifier on to supply DC power to the load.

Figure 5 is a diagram for explaining the operation of the AC-DC converter according to this embodiment.

As shown in FIG. 5, when the converter according to this embodiment blocks the power supply to the load of the above-mentioned faulty module and supplies power to the load only with the normal module, ripple occurs in the output power of the normal module and the power is turned off. It may fluctuate or decrease, causing abnormal conditions in the load.

Therefore, when the control unit 130 supplies power to a load using only the normal module, it detects the ripple value of the output power of the normal power control module and compares it with a set reference value. As a result of the comparison, if the ripple value of the output power is greater than the reference value, the reference duty ratio of the power switching element of the bidirectional bridgeless PFC of the normal power control module is increased to supply power to the load. That is, the bidirectional bridgeless PFC outputs higher power than the power used by the load. For reference, ZVS-PSFB is made from the power used by the load. Therefore, when supplying power to a load by reducing the number of normal power control modules, the output of the bidirectional bridgeless PFC is relatively increased to stably drive and protect the load.

The reference duty ratio is, for example, the duty ratio when supplying 1 kw as described above. The degree to which the reference duty ratio is increased is performed by setting different duty ratios for each number of loads supplying power.

For example, if the number of loads is two, the duty ratio can be increased to twice the standard duty ratio. In the case of 3, the same setting value can be used, and in the case of 5, a relatively higher setting value of 3 times can be used. The duty ratio can be added or subtracted in response to the DC power output value, such as 28V of a battery or fan.

In addition, when the converter supplies DC power to the load with the minimum output through a normal module, this minimum output is continuously supplied to the load, so the load may use a weak or unstable power source, causing an abnormal condition in the load. there is.

For this purpose, perform the following actions.

First, when supplying DC power to a load by limiting the output of each normal power control module according to the output ripple value, the control unit 120 counts the application time of the supplied DC power.

Then, the calculated application time of the DC power is compared with a set threshold time. As described above, the critical time can be added or subtracted in response to the DC power output value, such as 28V of the load battery, heater, or fan.

As a result of the comparison, if the calculated application time of the DC power is more than a set threshold time, the increased reference duty ratio is reduced by a first set value to protect the load. The first set value can be determined according to the DC power output value, load capacity, load type, etc.

For example, when the number of loads is two, the first set value can be set to 0.15 and reduced to the increased reference duty ratio × 0.15. The same setting values can be used in cases of 3 and 5.

Through this, in a converter failure situation, it is possible to prevent abnormal conditions in the load that may appear by continuing to supply power to the load with the minimum output that limits the ripple of the normal module.

Additionally, if this AC-DC converter supplies DC power to the load with only the power control module in a normal state, the DC power output may change or fluctuate if this module is used extensively, which may additionally indicate an abnormal state to the load.

The AC-DC converter first counts the usage time for each normal power control module in the control unit 130.

Then, the calculated normal use time of the power control module is compared with the rated use period of the set power control module.

As a result of the comparison, if the calculated normal use time of the power control module exceeds the rated use time of the set power control module, the increased reference duty ratio is reduced by a second set value to protect the load.

The second set value is determined by an abnormal state of the power control module and is set to a relatively higher value than the first set value described above. The specific value can be determined by considering the type of power control module, rated usage period, and maximum driving amount.

For example, when the number of loads is two, the second set value can be set to 0.3 and reduced to the increased reference duty ratio × 0.3. The same setting values can be used in cases of 3 and 5.

On the other hand, when the AC-DC converter supplies power to the load with only such a normal power control module, it is possible to further check whether or not it is replaced.

The control unit 130 sets values in a normal state as a reference value and a reference range for the transition value of the usage time of the normal power control module, and registers the reference value and the reference range.

In this state, the change in usage time of the normal power control module is calculated over a set period to calculate a trend value.

The calculated trend value is compared with the registered reference value, and if, as a result of the comparison, the calculated trend value differs from the registered reference value by more than a reference range, it is determined to be in a replacement state.

Additionally, when the normal power control module is in a replacement state, the control unit 130 protects the load by reducing the increased reference duty ratio by a third set value.

The third set value is according to the replacement state of the power control module and is relatively higher than the second set value according to the above-mentioned abnormal state. As above, the specific value is determined by considering the type of power control module, rated period of use, maximum drive amount, durability, etc.

For example, if the number of loads is two, the third set value can be set to 0.5 and reduced to the increased reference duty ratio × 0.5. The same setting values can be used in cases of 3 and 5.

Figure 6 is a block diagram showing the configuration of an AC-DC converter with a load sharing parallel structure according to an embodiment.

As shown in FIG. 6, the AC-DC converter 100 according to one embodiment largely includes a plurality of power control modules 110, a driver 120, and a control unit 130. Additionally, it includes an EMI filter 140, a DC output switch 150, and a display unit 160.

The plurality of power control modules 110 have a bidirectional bridgeless PFC, ZVS-PSFB, and synchronous rectifier as before.

The driver 120 is a first gate driver that commonly drives the power switching elements of the two-way bridgeless PFC of the multiple power control modules 110, and performs power switching of the ZVS-PSFB and synchronous rectifier for each of the multiple power control modules 110. It has a second gate driver that drives the device.

The control unit 130 first controls the first and second gate drivers to share the main DC power of the multiple power control modules 110 and supply it to the load. The supplied main DC power value is detected through a sensor, compared to a set reference value, and if there is a difference, the second gate driver of the faulty module is controlled to turn off the power switching device of the ZVS-PSFB. Then, the second gate driver of the normal module is controlled to keep the power switching element of the ZVS-PSFB on, and power is supplied to the load only with the normal module. For reference, the control unit 130 uses an MCU.

The EMI filter 140 removes electrical noise and supplies stable power when receiving the AC power.

The DC output switch 150 is used to control the output of DC power according to the user's key operation and supply it to the load.

The display unit 160 performs a power monitoring function on the lamp while operating the plurality of power control modules 110 to display the DC output status and AC input status and load amount. At this time, the lamp is provided for each of these various functions. In addition, the display unit 160 is turned on by the control unit 130 when there is an abnormality in the load and alarms the abnormal condition.

Figure 7 is a flow chart sequentially showing the operation of an AC-DC converter with a load sharing parallel structure according to an embodiment.

As shown in Figure 7, the AC-DC converter according to one embodiment is first equipped with a plurality of the above-described power control modules and installed in parallel (S701).

In addition, the AC-DC converter controls the first gate driver in the control unit to convert AC power to auxiliary DC power through each bidirectional bridgeless PFC of a plurality of power control modules.

The control unit controls a second gate driver for each of the plurality of power control modules, converts the auxiliary DC power into main DC power suitable for the load through ZVS-PSFB, and converts high frequency components from the main DC power through the synchronous rectifier. Isolate and supply to load.

In this state, the control unit detects the supplied DC power value through a sensor, compares it with a set reference value (S702), and determines an abnormal state if there is a difference (S703). Then, the second gate driver of the power control module in the determined abnormal state is controlled to turn off the power switching element of the ZVS-PSFB (S704), and the second gate driver of the power control module in the normal state is controlled to turn off the ZVS-PSFB. The power switching element is kept on (S705). Therefore, the power supply to the load is cut off from the faulty module, and power is supplied only to the normal module.

Through this, in the event of a failure in the converter used in a special vehicle, the AC input is maintained and the operating equipment continues to operate, thereby maintaining the operability of the operating equipment in use.

As described above, in one embodiment, when a failure of the AC-DC converter occurs in a special vehicle, the operational equipment continues to be operated to maintain the operability of the operational equipment in use. If there is no countermeasure for the failure of the AC-DC converter, it becomes impossible to operate the equipment in a failure situation. However, by overcoming this condition, AC input can be maintained.

100: AC-DC converter 110: Power control module
120: driving unit 130: control unit
140: EMI filter 150: DC output switch
160: display unit

Claims (6)

In AC-DC converter,
Multiple power sources including a bi-directional bridgeless PFC that receives AC power and converts it to DC power, a ZVS-PSFB that converts the DC power to the DC power of the load, and a synchronous rectifier that isolates the DC power of the load at high frequency and supplies it to the load. Control module 110;
A first gate driver driving the power switching elements of the bidirectional bridgeless PFC of the plurality of power control modules 110, and a second gate driver driving the power switching elements of the ZVS-PSFB and the synchronous rectifier for each of the plurality of power control modules 110. A driving unit 120 with two gate drivers; and
DC power is supplied to the load by controlling the first and second gate drivers of the driver 120, and the supplied DC power value is compared with a set reference value, and if there is a difference, the second gate driver of the power control module is controlled. It includes a control unit 130 that turns off the power switching element of the ZVS-PSFB to block the power supply to the load,

A voltage detection unit 111 that detects the voltage of the DC power of the plurality of power control modules and transmits it to the control unit 130; and
It further includes a temperature detection unit 112 that detects the ambient temperature of the voltage detection unit 111 and transmits it to the control unit 130,

The control unit 130 is
When cutting off the power supply to the load of the abnormal power control module, a first step of detecting the voltage of the output power of the normal power control module among the plurality of power control modules through the voltage detection unit 111;
A second step of comparing the voltage value detected in the first step with a set reference value;
A third step of detecting the surrounding external air temperature through the temperature sensing unit 112 when the voltage value compared in the second step is less than or equal to the reference value;
In the third step, the standard duty ratio determined by the number of loads is increased by 30% from -50℃ to 0℃, and the standard duty ratio is increased by 20% from 0℃ to 20℃, and 20℃. A fourth step of increasing the standard duty ratio by 10% until the temperature exceeds 50° C. or less; and
A fifth step of driving the power switching element of the bidirectional bridgeless PFC of the normal power control module according to the reference duty ratio increased in the fourth step. An AC-DC converter with a load sharing parallel structure comprising a.











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