阅读说明：本技术 用于补偿逆变器中死区的方法及系统 (method and system for compensating dead zone in inverter ) 是由 胡家喜 张少云 佘岳 黄敏 盛建科 徐凤星 谭宇 戴茜茜 江海啸 于 2018-05-28 设计创作，主要内容包括：本发明提供一种用于补偿逆变器中死区的方法,其包含以下步骤：采集逆变器中的功率单元的各桥臂上的实时电流信息；将电流信息传送给处理器,以进行控制计算生成脉冲信息；接收脉冲信息,并基于脉冲信息生成原始脉冲；根据实时电流信息中的方向信息,对原始脉冲的边沿中的部分进行脉冲调整得到优化脉冲,以补偿基于优化脉冲加入的死区所影响的电压值。本发明提供的一种用于补偿逆变器中死区的方法及系统能够对被补偿模块的死区时间进行补偿,不需要额外采集输出电压,实现方式简单。另外,采用过采样的方法采集信息,不需要额外的算法也能保证电流方向信息的可靠。并且,只是对脉冲的边沿做处理,可行性高。(The present invention provides a method for compensating a dead zone in an inverter, comprising the steps of: collecting real-time current information on each bridge arm of a power unit in an inverter; transmitting the current information to a processor for control calculation to generate pulse information; receiving pulse information and generating an original pulse based on the pulse information; according to the direction information in the real-time current information, pulse adjustment is carried out on the part in the edge of the original pulse to obtain an optimized pulse, so that the voltage value influenced by the dead zone added based on the optimized pulse is compensated. The method and the system for compensating the dead zone in the inverter can compensate the dead zone time of the compensated module without additionally acquiring output voltage, and the implementation mode is simple. In addition, the information is acquired by adopting an oversampling method, and the reliability of the current direction information can be ensured without an additional algorithm. And, only the edge of the pulse is processed, and the feasibility is high.)

1. A method for compensating for dead band in an inverter, the method comprising the steps of:

Collecting real-time current information on each bridge arm of a power unit in the inverter;

Transmitting the current information to a processor for control calculation to generate pulse information;

Receiving the pulse information and generating an original pulse based on the pulse information;

and according to the direction information in the real-time current information, pulse adjustment is carried out on the part in the edge of the original pulse to obtain an optimized pulse so as to compensate the voltage value influenced by the dead zone added based on the optimized pulse.

2. the method for compensating for dead band in an inverter of claim 1, wherein the acquisition period is less than the control calculation period.

3. The method for compensating for dead band in an inverter of claim 1, wherein collecting real-time current information on each leg of a power cell in the inverter further comprises the steps of:

collecting analog current signals on each bridge arm of a power unit in the inverter;

and converting the analog current signal into a digital current signal to obtain the current.

4. The method for compensating for dead band in an inverter according to claim 1, wherein the step of performing the control calculation to generate the pulse information further comprises the steps of:

And tracking the real-time current, and adjusting the pulse width according to the tracked real-time result and the target current to obtain the pulse information.

5. The method for compensating for dead band in an inverter of claim 1, further comprising: when the direction information is flowing out of the inverter, the step of performing pulse adjustment on the part in the edge of the original pulse to obtain an optimized pulse further comprises the following steps:

and at the rising edge moment of the original pulse, not adjusting the original pulse, and at the falling edge moment of the original pulse, performing time delay processing on the original pulse.

6. The method for compensating for dead band in an inverter of claim 1, further comprising: when the direction information is flowing into the inverter, the step of performing pulse adjustment on the portion of the edge of the original pulse to obtain an optimized pulse further comprises the following steps:

And delaying the original pulse at the rising edge of the original pulse, and not adjusting the original pulse at the falling edge of the original pulse.

7. An inverter system with dead band compensation, the system comprising:

A power unit including a leg of the inverter, wherein the leg outputs real-time current information;

The processor is used for receiving the current information to perform control calculation to generate pulse information;

A programmable logic device configured to:

collecting real-time current information on each bridge arm of the power unit;

transmitting the current information to a processor for control calculation to generate pulse information;

Receiving the pulse information and generating an original pulse based on the pulse information;

and according to the direction information in the real-time current information, pulse adjustment is carried out on the part in the edge of the original pulse to obtain an optimized pulse so as to compensate the voltage value influenced by the dead zone added based on the optimized pulse.

8. The inverter system with dead-time compensation of claim 7, wherein the system comprises an analog-to-digital converter for collecting analog current signals on each leg of a power cell in the inverter and converting the analog current signals to digital current signals to obtain the current information.

9. The inverter system with dead band compensation of claim 7, wherein the programmable logic device is further configured to:

And tracking the real-time current, and adjusting the pulse width according to the tracked real-time result and the target current to obtain the pulse information.

10. The inverter system with dead band compensation of claim 7, wherein the programmable logic device is further configured to:

And according to the direction information in the real-time current information, performing time delay processing on the part in the edge of the original pulse to obtain an optimized pulse.

Technical Field

The invention relates to the technical field of electronics, in particular to a method and a system for compensating a dead zone in an inverter.

Background

Any solid state power electronic device has certain on and off times, such as: in the voltage source inverter, in order to ensure that an upper bridge arm and a lower bridge arm are not simultaneously conducted, the time for simultaneously turning off the bridge arms must be added in the process of alternately conducting the upper bridge arm and the lower bridge arm, and the time is called dead time.

Due to the existence of the dead zone, the output voltage of the converter and the target output voltage have amplitude and phase deviation, so that the amplitude of the fundamental voltage is reduced, and the output performance is influenced; in addition, the current waveform is distorted, torque ripple is caused, and system harmonics are increased.

Accordingly, the present invention provides a method and system for compensating for dead band in an inverter.

Disclosure of Invention

To solve the above problems, the present invention provides a method for compensating for a dead zone in an inverter, the method comprising the steps of:

Collecting real-time current information on each bridge arm of a power unit in the inverter;

transmitting the current information to a processor for control calculation to generate pulse information;

receiving the pulse information and generating an original pulse based on the pulse information;

And according to the direction information in the real-time current information, pulse adjustment is carried out on the part in the edge of the original pulse to obtain an optimized pulse so as to compensate the voltage value influenced by the dead zone added based on the optimized pulse.

According to one embodiment of the invention, the acquisition period is less than the control calculation period.

according to an embodiment of the present invention, the step of collecting real-time current information on each leg of the power unit in the inverter further comprises the steps of:

Collecting analog current signals on each bridge arm of a power unit in the inverter;

And converting the analog current signal into a digital current signal to obtain the current information.

according to an embodiment of the present invention, the step of performing the control calculation to generate the pulse information further comprises the steps of:

and tracking the real-time current, and adjusting the pulse width according to the tracked real-time result and the target current to obtain the pulse information.

According to one embodiment of the invention, the method further comprises: when the direction information is flowing out of the inverter, the step of performing pulse adjustment on the part in the edge of the original pulse to obtain an optimized pulse further comprises the following steps:

and at the rising edge moment of the original pulse, not adjusting the original pulse, and at the falling edge moment of the original pulse, performing time delay processing on the original pulse.

According to one embodiment of the invention, the method further comprises: when the direction information is flowing into the inverter, the step of performing pulse adjustment on the portion of the edge of the original pulse to obtain an optimized pulse further comprises the following steps:

And delaying the original pulse at the rising edge of the original pulse, and not adjusting the original pulse at the falling edge of the original pulse.

according to another aspect of the present invention, there is also provided an inverter system with dead zone compensation, the system including:

a power unit including a leg of the inverter, wherein the leg outputs real-time current information;

The processor is used for receiving the current information to perform control calculation to generate pulse information;

A programmable logic device configured to:

collecting real-time current information on each bridge arm of the power unit;

Transmitting the current information to a processor for control calculation to generate pulse information;

receiving the pulse information and generating an original pulse based on the pulse information;

And according to the direction information in the real-time current information, pulse adjustment is carried out on the part in the edge of the original pulse to obtain an optimized pulse so as to compensate the voltage value influenced by the dead zone added based on the optimized pulse.

According to one embodiment of the invention, the system comprises an analog-to-digital converter for acquiring analog current signals on each bridge arm of a power unit in the inverter and converting the analog current signals into digital current signals to obtain the current information.

according to one embodiment of the invention, the programmable logic device is further configured to:

And tracking the real-time current, and adjusting the pulse width according to the tracked real-time result and the target current to obtain the pulse information.

According to one embodiment of the invention, the programmable logic device is further configured to:

and according to the direction information in the real-time current information, performing time delay processing on the part in the edge of the original pulse to obtain an optimized pulse.

the method and the system for compensating the dead zone in the inverter can compensate the dead zone time of the compensated module without additionally acquiring output voltage, and the implementation mode is simple. In addition, the information is acquired by adopting an oversampling method, and the reliability of the current direction information can be ensured without an additional algorithm. And, only the edge of the pulse is processed, and the feasibility is high.

Additional features and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.

Drawings

The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention and not to limit the invention. In the drawings:

FIG. 1 shows a circuit diagram of an inverter leg;

FIG. 2 is a graph showing an output waveform of an inverter under the influence of a dead zone;

FIG. 3 shows a flowchart of a method for compensating for dead band in an inverter according to one embodiment of the invention;

FIG. 4 shows a block diagram of a system architecture for compensating for dead band in an inverter according to one embodiment of the present invention;

FIG. 5 shows a flowchart of a method for compensating for dead band in an inverter according to another embodiment of the invention; and

Fig. 6 shows a waveform diagram of an output of an inverter after dead-zone compensation according to an embodiment of the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, embodiments of the present invention are described in further detail below with reference to the accompanying drawings.

Any solid state power electronic device has certain on and off times, such as: in the voltage source inverter, in order to ensure that an upper bridge arm and a lower bridge arm are not simultaneously conducted, the time for simultaneously turning off the bridge arms must be added in the process of alternately conducting the upper bridge arm and the lower bridge arm, and the time is called dead time. Due to the addition of the dead zone, the actual output waveform of the inverter is different from the expected output waveform, and the following analysis is performed by taking one bridge arm of the inverter as an example, and fig. 1 shows a circuit diagram of the bridge arm of the inverter.

As shown in fig. 1. It is known that the on and off of the power device requires a certain time, so as to avoid the upper and lower tubes (VT1 and VT2) from forming a path, and generating a through current to damage the device, and therefore, the dead time, namely the delay td (dead time), is inserted to give an on signal. During the time when the upper and lower tubes are both off, the freewheeling is achieved by the diodes (VD1 and VD 2).

with the inverter current bleed positive as shown in fig. 2. When the rising edge of the original pulse comes, the VT2 is normally closed, and the VT1 is switched on in a time delay td; when the original pulse falling edge comes, the VT1 is normally closed, and the VT2 is switched on in a time delay td; since the current direction is out, the inverter output voltage is zero during the dead time, which is freewheeling via VD 2.

As described above, in this condition, the pulse width between the waveform of the final output voltage and the expected output voltage waveform (original pulse) is reduced by the width td. The dead zone has obvious influence on the control performance of the system on the occasions that the output voltage of the inverter is low and the switching frequency is high.

therefore, there is a need for a method and system for compensating for dead time in an inverter to compensate for dead time of the inverter. Currently, there are two main directions for studying dead-zone compensation, one is a voltage feedback compensation method, and the other is a current-based compensation method.

The voltage feedback compensation method firstly detects the actual output voltage of the system inversion unit, then compares the actual output voltage with the instruction voltage, and superposes the difference value as compensation quantity on the instruction voltage as a new instruction. Since the deviation voltage is directly detected rather than estimated and has the idea of quasi-closed loop control for the output voltage, any error of the output voltage and the command voltage (including the switching dead time of the device) caused by an inverter unit in a loop can be eliminated in principle, and the compensation effect is good without being influenced by the change of the load current.

the compensation method based on the current detects the output current of the inverter, adds dead zone compensation time before the pulse generates distortion, so that the compensated pulse is completely close to or reaches the waveform under an ideal state on the pulse width and the phase position, and the compensation purpose is achieved. In order to eliminate the influence of the accuracy of current detection, many optimization schemes are proposed, such as compensation methods based on current feed-forward, compensation based on rotation coordinates, compensation based on current prediction, and the like.

however, the current methods based on voltage and current compensation all have certain disadvantages, such as: a pulse width modulation variable frequency power supply and a dead zone compensation method (CN201010042864.1) thereof, a high-precision dead zone compensation method and device (CN201510964194) based on an FPGA and other patent documents all adopt a voltage compensation method, and the defect is that the structure is too complex, an additional voltage detection circuit is needed, and because the dead zone time value is very small, the detection precision of a voltage detection link is required to be high enough, and a good compensation effect can be ensured without time lag. If the method is realized by a digital method, not only the algorithm is complex, but also the requirement on the speed of data processing is high.

patent documents: the dead zone compensation system and method (CN201210388790.6), the dead zone compensation method (CN00122378.X) of the frequency converter and the like adopt a current compensation scheme. In order to eliminate the influence of current sampling and zero crossing points on dead zone compensation, the method is complex and has high requirements on a control system.

Therefore, in order to better compensate for the dead time of the electronic power device, fig. 3 shows a flowchart of a method for compensating for the dead time in the inverter according to an embodiment of the present invention. As shown in fig. 3, in step S301, real-time current information on each arm of the power cells in the inverter is collected.

according to an embodiment of the present invention, in the step of acquiring the real-time current information on each bridge arm of the power unit in the inverter, it is required to first acquire an analog current signal on each bridge arm of the power unit in the inverter, and then convert the analog current signal into a digital current signal, so as to obtain the current information.

Next, in step S302, the current information is transmitted to the processor to perform control calculation to generate pulse information. The content of the control calculation includes pulse width adjustment of the current information to obtain pulse information. It should be noted that the period of acquisition is smaller than the period of control calculation, and the period of control calculation may be an integral multiple of the period of acquisition, or may be a non-integral multiple.

then, in step S303, pulse information is received, and an original pulse is generated based on the pulse information. The original pulse is original pulse information of the inverter, amplitude and phase deviation exists after dead time, and in order to compensate the influence of the dead time on the current of the inverter, finally, in step S304, according to the direction information in the real-time current information, pulse adjustment is performed on a part in the edge of the original pulse to obtain an optimized pulse so as to compensate the voltage value influenced by the dead time added based on the optimized pulse.

According to one embodiment of the invention, when the current direction is flowing out of the inverter, the original pulse is not adjusted at the rising edge time of the original pulse, and the original pulse is subjected to time delay processing at the falling edge time of the original pulse. When the current flows into the inverter, the original pulse is subjected to time delay processing at the rising edge moment of the original pulse, and the original pulse is not adjusted at the falling edge moment of the original pulse.

fig. 4 shows a block diagram of a system configuration for compensating for dead zones in an inverter according to an embodiment of the present invention. The method for compensating the dead zone in the inverter provided by the invention can be applied to the inverter shown in fig. 4, and the dead zone time of the inverter is compensated. As shown in fig. 4, the inverter is mainly composed of a processor 401, a programmable logic device 402, and a power unit 403. Additionally, the system may also include an analog-to-digital converter 404.

The system shown in fig. 4 can collect analog quantities such as current of the inverter, and the dead-time compensation method proposed by the present invention can be applied to perform switching control on the power electrical devices of the power unit 403 through the PWM pulses, so that the inverter can output a desired voltage.

as shown in fig. 4, a power cell includes a leg of an inverter, wherein the leg outputs real-time current information. The processor is used for receiving the current information to perform control calculation to generate pulse information; a programmable logic device configured to: collecting real-time current information on each bridge arm of a power unit; transmitting the current information to a processor for control calculation to generate pulse information; receiving pulse information and generating an original pulse based on the pulse information; according to the direction information in the real-time current information, pulse adjustment is carried out on the part in the edge of the original pulse to obtain an optimized pulse, so that the voltage value influenced by the dead zone added based on the optimized pulse is compensated.

according to one embodiment of the invention, the processor 401 is primarily responsible for controlling the algorithm portion; the programmable logic device 402 is responsible for generating PWM pulses and controlling A/D conversion according to the information of the processor 401; the analog-to-digital converter 404 includes an a/D conversion chip and an analog conditioning circuit, and is responsible for collecting analog quantities such as current. It should be noted that the processor may be any type of DSP, programmable logic device, and the analog-to-digital converter may be any type of device, and other devices capable of achieving the purpose of the present invention may also be applied to the present invention, which is not limited thereto.

According to one embodiment of the invention, the programmable logic device is further configured to: and tracking the real-time current, and adjusting the pulse width according to the tracked real-time result and the target current to obtain pulse information. According to one embodiment of the invention, the programmable logic device is further configured to: and according to the direction information in the real-time current information, delaying the part in the edge of the original pulse to obtain an optimized pulse.

fig. 5 shows a flow chart of a method for compensating for dead band in an inverter according to another embodiment of the invention.

As shown in fig. 5, in step S501, control calculation is performed using the latest a/D sampling data to generate PWM pulse information. Sampling in this step may apply current flow sampling. Current sampling mainly refers to that the sampling period of the programmable logic device for controlling A/D conversion is smaller than the period of the processor for performing control calculation by using analog quantity, and the calculation period of the processor can be integral multiple of the A/D conversion period (synchronous sampling) or non-integral multiple (asynchronous sampling). The performer of step S501 may be a DSP.

next, in step S502, the programmable logic device generates an original PWM pulse according to the PWM pulse information sent by the processor. In step S501, the programmable logic device can obtain real-time current information through fast current sampling. The programmable logic device can generate the original PWM pulse of the inverter according to the PWM pulse information sent by the processor.

Then, in step S503, the pulse is adjusted for the rising edge and the falling edge on the basis of the original PWM pulse according to the current direction. According to one embodiment of the present invention, the relationship between the adjusted PMW pulse and the original PWM pulse is shown in table 1 below. (defining the current flowing out of the inverter as positive and the current flowing into the converter as negative with a dead time td)

TABLE 1 adjustment table

	The current direction is as follows: is just	the current direction is as follows: negative pole
			Rising edge	Is not adjusted	dTime delay td
Falling edge	dTime delay td	is not adjusted

Finally, in step S504, a dead zone is generated based on the adjusted pulse, and finally output to the upper and lower arms. Therefore, dead zone compensation of the inverter can be completed. The performers of step S502, step S503, and step S504 are programmable logic devices.

Fig. 6 shows a waveform diagram of an output of an inverter after dead-zone compensation according to an embodiment of the present invention. Fig. 6 is a simplified illustration of the pulse adjustment and transmission when the current direction is positive. Time 1 is the rising edge of the original pulse, and according to table 1, no adjustment is made to the pulse; time 2 is the falling edge of the original pulse, which is delayed by td according to table 1; at the moment 3, a dead zone is generated, the lower bridge arm is immediately turned off, and the upper bridge arm is turned on in a delayed manner td; and at the moment 4, a dead zone is generated, the upper bridge arm is immediately turned off, and the bridge arm is turned on in a delayed manner.

Since the output current is mainly the output current and the current is freewheeling through the upper arm diode during the dead zone, the final output voltage waveform width is the same as the upper arm pulse width, and it can be seen from fig. 6 that the final output voltage waveform width is the same as the original pulse width expected by the processor. As shown in fig. 5 and 6, the programmable logic device performs partial delay processing on the rising edge and the falling edge of the original pulse according to the direction information of the current, so as to obtain an adjusted pulse, and then performs the production of the dead zone on the basis of the pulse.

The dead zone compensation method and the system provided by the invention can compensate the dead zone time of the compensated module without additionally acquiring output voltage, and the implementation mode is simple. In addition, the information is acquired by adopting an oversampling method, and the reliability of the current direction information can be ensured without an additional algorithm. And, only the edge of the pulse is processed, and the feasibility is high.

It is to be understood that the disclosed embodiments of the invention are not limited to the particular structures, process steps, or materials disclosed herein but are extended to equivalents thereof as would be understood by those ordinarily skilled in the relevant arts. It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only, and is not intended to be limiting.

reference in the specification to "one embodiment" or "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the invention. Thus, the appearances of the phrase "one embodiment" or "an embodiment" in various places throughout this specification are not necessarily all referring to the same embodiment.

Although the embodiments of the present invention have been described above, the above description is only for the convenience of understanding the present invention, and is not intended to limit the present invention. It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.