CN109995233B - Hybrid PWM control method and device - Google Patents
Hybrid PWM control method and device Download PDFInfo
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- CN109995233B CN109995233B CN201810005923.4A CN201810005923A CN109995233B CN 109995233 B CN109995233 B CN 109995233B CN 201810005923 A CN201810005923 A CN 201810005923A CN 109995233 B CN109995233 B CN 109995233B
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M3/00—Conversion of dc power input into dc power output
- H02M3/02—Conversion of dc power input into dc power output without intermediate conversion into ac
- H02M3/04—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters
- H02M3/10—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
- H02M3/145—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
- H02M3/155—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M1/00—Details of apparatus for conversion
- H02M1/0048—Circuits or arrangements for reducing losses
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M1/00—Details of apparatus for conversion
- H02M1/0048—Circuits or arrangements for reducing losses
- H02M1/0054—Transistor switching losses
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
- Y02B70/00—Technologies for an efficient end-user side electric power management and consumption
- Y02B70/10—Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes
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- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Dc-Dc Converters (AREA)
- Rectifiers (AREA)
Abstract
The invention relates to a hybrid PWM control method and a device, wherein the control method comprises the following steps: detecting the output voltage and the output current of the converter in real time, and further calculating a PI control output value; judging the PI control output value, if the PI control output value is smaller than the first control parameter and larger than the second control parameter, setting the on-time of a switch tube in the converter as a function of the output voltage of the converter to reduce the frequency of the switch tube, wherein the larger the output voltage of the converter is, the larger the on-time of the switch tube in the converter is; and controlling the converter according to the set on-time of a switching tube in the converter. The invention can increase the on-time of the frequency converter, and simultaneously control and reduce the switching frequency of the power supply, and the reduction of the switching frequency can reduce the loss of the power device and the magnetic device.
Description
Technical Field
The invention relates to a hybrid PWM control method and device, and belongs to the technical field of new energy vehicles.
Background
With the commercialization of new energy industries and the national requirements for energy conservation and emission reduction, high-voltage and high-power supplies gradually become the trend of power supply development. The application of power electronics is developing towards high integration and high efficiency, and simultaneously, higher requirements are put on the management of power supplies.
In the field of vehicle-mounted charging of new energy vehicles, a three-level BUCK circuit, namely a three-level dc converter, is a non-isolated topology widely applied, and a schematic structural diagram of the three-level BUCK circuit is shown in fig. 1, and includes two voltage-dividing capacitors C1 and C2, two power switches Q1 and Q2, two freewheeling diodes D1 and D2, a filter inductor L1, and the like.
When the duty ratio D is less than 0.5, the current variation of each device in the three-level dc converter is as shown in fig. 2, and the operation process is as follows:
when the Q1 is turned on and the Q2 is turned off, the capacitor C1 supplies energy to the inductor L1 and the load, and the inductor current shows a positive slope rising.
When Q1 is turned off and Q2 is turned off, the inductor current drops with a negative slope, and the inductor L1 supplies energy to the load.
When the Q1 is turned off and the Q2 is turned on, the capacitor C2 supplies energy to the inductor L1 and the load, and the inductor current shows a positive slope rising.
4. The above phases are cycled.
When the duty ratio D >0.5, the current variation of each device in the three-level dc converter is as shown in fig. 3, and the operation process is as follows:
when the Q1 is turned on and the Q2 is turned on simultaneously, the power supply supplies energy to the inductor L1 and the load, and the inductor current rises with a positive slope.
Q1 is off, Q2 is still in the on-phase, inductor current exhibits a negative slope drop, and inductor L1 provides energy to the load.
When Q2 is turned on simultaneously with Q1 turned on again, the power supply supplies energy to inductor L1 and the load, and the inductor current rises with a positive slope.
4. The above phases are cycled.
The topology of the three-level BUCK can be derived with a transfer function Vo — Vin × D (CCM mode is applicable), where Vin is the input voltage and Vo is the output voltage. It can be known from the transfer function that when the BUCK is applied to output a wide range of power, the output is in a low-voltage full-load state, the duty ratio is very small, and the on-time is very short. When the output voltage is the minimum Vomin, the duty ratio corresponding to the voltage is the minimum duty ratio Dmin, and the minimum duty ratio means that under the output condition of low voltage and full load, the on-off time has larger instantaneous current, and meanwhile, the effective value of the inductive current is larger. Assuming that the output voltage is V1 and the output power is P1, different conduction times are set under the same power and voltage conditions, when the conduction time is Ton1, the peak current is IP1, and the effective value current is RMS 1; when the on-time is Ton2, the peak current is IP2 and the effective value current is RMS 2. As can be seen from fig. 4, the peak current obtained by the control with the small on-time is much larger than that obtained by the control with the long on-time.
As can be derived from the formula P _ swing _ loss of the switching loss in the three-level BUCK of 0.5 Vo Ip (Ton + toff), the switching loss during the switching period of Ton1 is much greater than the switching loss during the switching period of Ton 2. From the formula of the conduction loss P _ con _ loss ═ RMS ^2 × Rdson, it can be deduced that the effective value current obtained by the control with the small conduction time is much larger than that obtained by the control with the long conduction time. In summary, when the on-time or the duty ratio is small, the peak current of the on-state and the peak current of the off-state are large, which results in large on-state and off-state losses, and the effective value current of the inductor is also large.
Disclosure of Invention
The invention aims to provide a hybrid PWM control method and a hybrid PWM control device, which are used for solving the problem of large loss of an inverter.
In order to solve the technical problem, the invention provides a hybrid PWM control method, which comprises the following schemes:
the first method scheme is as follows: the method comprises the following steps:
detecting the output voltage and the output current of the converter in real time, and further calculating a PI control output value;
judging the PI control output value, if the PI control output value is smaller than the first control parameter and larger than the second control parameter, setting the on-time of a switch tube in the converter as a function of the output voltage of the converter to reduce the frequency of the switch tube, wherein the larger the output voltage of the converter is, the larger the on-time of the switch tube in the converter is;
and controlling the converter according to the set on-time of a switching tube in the converter.
The second method comprises the following steps: on the basis of the first method scheme, if the PI control output value is judged to be larger than the first control parameter, duty ratio PWM control is carried out on the converter.
The third method scheme is as follows: on the basis of the first method scheme or the second method scheme, if the PI control output value is judged to be smaller than the second control parameter, duty ratio PWM control is carried out on the converter.
The method scheme is as follows: on the basis of the first or second method scheme, the expression of the on-time of the switching tube in the converter is as follows:
Ton＝(Vo-3)/c
wherein, TonFor setting the on-time of the switching tube in the converter, VoC is a correlation coefficient, which is the output voltage of the converter, and is determined by the switching frequency of the power supply.
The invention also provides a hybrid PWM control device, which comprises the following scheme:
the first device scheme is as follows: comprising a processor and a memory, the processor for processing instructions stored in the memory to implement the method of:
detecting the output voltage and the output current of the converter in real time, and further calculating a PI control output value;
judging the PI control output value, if the PI control output value is smaller than the first control parameter and larger than the second control parameter, setting the on-time of a switch tube in the converter as a function of the output voltage of the converter to reduce the frequency of the switch tube, wherein the larger the output voltage of the converter is, the larger the on-time of the switch tube in the converter is;
and controlling the converter according to the set on-time of a switching tube in the converter.
The device scheme II comprises the following steps: on the basis of the first device aspect, the processor is further configured to process instructions stored in the memory to implement the following method:
and if the PI control output value is judged to be larger than the first control parameter, performing duty ratio PWM control on the converter.
The device scheme is as follows: on the basis of the first or second device aspect, the processor is further configured to process instructions stored in the memory to implement the following method:
and if the PI control output value is judged to be smaller than the second control parameter, performing duty ratio PWM control on the converter.
The device scheme is four: on the basis of the first device scheme or the second device scheme, the expression of the on-time of a switching tube in the converter is as follows:
Ton＝(Vo-3)/c
wherein, TonFor setting the on-time of the switching tube in the converter, VoC is a correlation coefficient, which is the output voltage of the converter, and is determined by the switching frequency of the power supply.
The invention has the beneficial effects that: by judging the PI control output value of the converter in real time, when the PI control output value is smaller than the first control parameter and larger than the second control parameter, the on-time of a switch tube in the converter is set as a function of the output voltage of the converter to reduce the frequency of the switch tube, at the moment, the corresponding converter output voltage ratio is lower, the load is heavier, the on-time can be increased, the power supply switching frequency is controlled to be reduced, and the loss of a power device and a magnetic device can be reduced due to the reduction of the switching frequency.
Drawings
FIG. 1 is a topology of a three-level converter;
FIG. 2 is a waveform analysis diagram of the topology of the three-level converter at a duty cycle of less than 0.5;
FIG. 3 is a waveform analysis plot of the topology of the three-level converter at duty cycles greater than 0.5;
FIG. 4 is a schematic diagram of inductor current versus duty cycle;
FIG. 5 is a flow chart of a hybrid PWM control method of the present invention;
FIG. 6 is a schematic diagram of voltage versus duty cycle in pure PWM control;
FIG. 7 is a schematic diagram of the relationship between voltage and duty cycle in the hybrid PWM control method of the present invention;
fig. 8 is a schematic diagram of the relationship between the hybrid PWM control and the frequency.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention will be described in further detail with reference to the accompanying drawings and specific embodiments.
The invention provides a hybrid PWM control device, which comprises a processor and a memory, wherein the processor is used for processing instructions stored in the memory and is used for realizing a hybrid PWM control method, the control method has 3 sections for controlling the duty ratio, and the three sections are mutually independent. Wherein, in paragraphs 0-k 2: performing PWM control; at paragraphs k2-k 1: performing frequency modulation and PWM control; after paragraph k 1: and performing PWM control. In this embodiment, taking a three-level converter as an example, a flowchart of the hybrid PWM control method is shown in fig. 5, and specifically includes the following steps:
(1) and detecting the output voltage and the output current of the three-level converter in real time, and further calculating a PI control output value.
In the embodiment, the PI output value k0 controlled in the three-level converter, namely the BUCK circuit, is obtained through closed-loop detection and control calculation. Of course, as another embodiment, the PI control output value k0 may be obtained by another method.
(2) Judging the PI control output value, comparing the PI control output value with control variables, namely a first control parameter k1 and a second control parameter k2, set by a system, and further determining the control mode of the three-level converter according to the comparison result, wherein the method specifically comprises the following steps:
1) the control quantity in the current state, i.e., the PI control output value k0, is compared with the set value of the system, i.e., the control variable first control parameter k1 and the second control parameter k2 set by the system. If the current control value k0 is greater than k1 and k2, pure duty PWM control is performed. The output voltage corresponding to the control at the moment is higher, the duty ratio is larger, and the efficiency is very high.
2) The comparison of the control quantity in the current state, i.e., the PI control output value k0, with the set value of the system, i.e., the control variable first control parameter k1 and the second control parameter k2 set by the system, is continued. If the current control value k0 is smaller than k1 and larger than k2, fitting a function inside the DSP, and setting the turn-on time of the switching tube in the three-level converter as a function of the output voltage of the three-level converter to reduce the frequency of the switching tube, wherein the larger the output voltage of the three-level converter is, the larger the turn-on time of the switching tube in the three-level converter is.
Specifically, in this embodiment, the expression of the on-time of the switching tube in the three-level converter is set as follows:
Ton＝(Vo-3)/c
wherein, TonFor setting the on-time, V, of a switching tube in a three-level converteroIs the output voltage of the three-level converter, and c is a correlation coefficient determined by the switching frequency of the power supply.
The on-time and the working frequency of the work are confirmed through the function, at the moment, the corresponding output voltage is lower, the load is heavier, the on-time can be increased through the implementation of the control process, the switching frequency of the power supply is controlled and reduced, and the loss of the power device and the magnetic device can be reduced through the reduction of the switching frequency.
3) When the output voltage is too low and the load current is small, if the above strategy is continued, the switching frequency becomes very low, the alternating magnetic flux density of the inductor is too high, saturation is easy, and problems occur. Therefore, if the current control value is less than k1 and less than k2, duty cycle PWM control is used at this stage. Since the load at this time is small, the problem of excessive loss due to PWM control is negligible.
When the control is performed by using the simple PWM, a graph of the variation between the output voltage Vo and the duty ratio D of the three-level converter is shown in fig. 6. When the hybrid PWM control method is adopted for control, a change curve chart between the output voltage Vo and the duty ratio D of the three-level converter is shown in FIG. 7, and a relation diagram between the hybrid control PWM and the frequency is correspondingly given in FIG. 8.
According to the invention, through a three-section type hybrid control mode, the limitation of pure PWM control is eliminated, the conduction time of a low-voltage full-load output state is prolonged, the BUCK loss is reduced, the efficiency is improved, and higher efficiency can be realized when low voltage is output. It should be noted that the hybrid PWM control method and apparatus are only specifically described by taking a three-level converter as an example, but are not limited to the application of the three-level converter, and are also applicable to other converter PWM controls.
Claims (4)
1. A hybrid PWM control method is characterized by comprising the following steps:
detecting the output voltage and the output current of the converter in real time, and further calculating a PI control output value;
judging the PI control output value, if the PI control output value is smaller than the first control parameter and larger than the second control parameter, setting the on-time of a switch tube in the converter as a function of the output voltage of the converter to reduce the frequency of the switch tube, wherein the larger the output voltage of the converter is, the larger the on-time of the switch tube in the converter is;
controlling the converter according to the set on-time of a switching tube in the converter;
the converter is a three-level BUCK circuit;
if the PI control output value is judged to be larger than the first control parameter, duty ratio PWM control is carried out on the converter;
and if the PI control output value is judged to be smaller than the second control parameter, performing duty ratio PWM control on the converter.
2. The hybrid PWM control method according to claim 1, wherein the expression of the on-time of the switching tube in the inverter is set as:
Ton＝(Vo-3)/c
wherein, TonFor setting the on-time of the switching tube in the converter, VoC is a correlation coefficient, which is the output voltage of the converter, and is determined by the switching frequency of the power supply.
3. A hybrid PWM control apparatus, comprising a processor and a memory, the processor being configured to process instructions stored in the memory to implement the following method:
detecting the output voltage and the output current of the converter in real time, and further calculating a PI control output value;
judging the PI control output value, if the PI control output value is smaller than the first control parameter and larger than the second control parameter, setting the on-time of a switch tube in the converter as a function of the output voltage of the converter to reduce the frequency of the switch tube, wherein the larger the output voltage of the converter is, the larger the on-time of the switch tube in the converter is;
controlling the converter according to the set on-time of a switching tube in the converter;
the converter is a three-level BUCK circuit;
the processor is further configured to process instructions stored in the memory to implement the following method:
if the PI control output value is judged to be larger than the first control parameter, duty ratio PWM control is carried out on the converter;
the processor is further configured to process instructions stored in the memory to implement the following method:
and if the PI control output value is judged to be smaller than the second control parameter, performing duty ratio PWM control on the converter.
4. A hybrid PWM control apparatus according to claim 3, wherein the switching tube on time in the inverter is expressed by:
Ton＝(Vo-3)/c
wherein, TonFor setting the on-time of the switching tube in the converter, VoC is a correlation coefficient, which is the output voltage of the converter, and is determined by the switching frequency of the power supply.
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Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1992493A (en) * | 2005-12-30 | 2007-07-04 | 艾默生网络能源系统有限公司 | Resonant DC/DC converter and control method thereof |
| CN101867296A (en) * | 2010-06-01 | 2010-10-20 | 国电南瑞科技股份有限公司 | Series-resonant direct-current/direct-current converter |
| CN102136797A (en) * | 2010-09-08 | 2011-07-27 | 上海岩芯电子科技有限公司 | Modulating method for noninverting Buck-Boost power inverter |
| JP2016189654A (en) * | 2015-03-30 | 2016-11-04 | サンケン電気株式会社 | Current resonant converter |
| CN106208751A (en) * | 2015-04-30 | 2016-12-07 | 福州瑞芯微电子股份有限公司 | Inverse-excitation type switch power-supply and control method thereof |
| CN106787776A (en) * | 2015-11-23 | 2017-05-31 | 池州学院 | A kind of LLC resonant converter for mixing control |
-
2018
- 2018-01-03 CN CN201810005923.4A patent/CN109995233B/en active Active
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1992493A (en) * | 2005-12-30 | 2007-07-04 | 艾默生网络能源系统有限公司 | Resonant DC/DC converter and control method thereof |
| CN101867296A (en) * | 2010-06-01 | 2010-10-20 | 国电南瑞科技股份有限公司 | Series-resonant direct-current/direct-current converter |
| CN102136797A (en) * | 2010-09-08 | 2011-07-27 | 上海岩芯电子科技有限公司 | Modulating method for noninverting Buck-Boost power inverter |
| JP2016189654A (en) * | 2015-03-30 | 2016-11-04 | サンケン電気株式会社 | Current resonant converter |
| CN106208751A (en) * | 2015-04-30 | 2016-12-07 | 福州瑞芯微电子股份有限公司 | Inverse-excitation type switch power-supply and control method thereof |
| CN106787776A (en) * | 2015-11-23 | 2017-05-31 | 池州学院 | A kind of LLC resonant converter for mixing control |
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Address after: 450061 Yutong Road, Guancheng District, Zhengzhou City, Henan Province Patentee after: Yutong Bus Co., Ltd Address before: 450016 shibalihe Yutong Industrial Park, Zhengzhou City, Henan Province Patentee before: Zhengzhou Yutong Bus Co., Ltd |