WO2022224437A1 - 電力変換装置及び電力変換装置の制御方法 - Google Patents
電力変換装置及び電力変換装置の制御方法 Download PDFInfo
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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
- H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
- H02M7/42—Conversion of dc power input into ac power output without possibility of reversal
- H02M7/44—Conversion of dc power input into ac power output without possibility of reversal by static converters
- H02M7/48—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
- H02M7/53—Conversion of dc power input into ac power output without possibility of reversal 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
- H02M7/537—Conversion of dc power input into ac power output without possibility of reversal 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, e.g. single switched pulse inverters
- H02M7/5387—Conversion of dc power input into ac power output without possibility of reversal 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, e.g. single switched pulse inverters in a bridge configuration
- H02M7/53871—Conversion of dc power input into ac power output without possibility of reversal 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, e.g. single switched pulse inverters in a bridge configuration with automatic control of output voltage or current
- H02M7/53873—Conversion of dc power input into ac power output without possibility of reversal 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, e.g. single switched pulse inverters in a bridge configuration with automatic control of output voltage or current with digital control
-
- 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
- H02M1/0003—Details of control, feedback or regulation circuits
- H02M1/0025—Arrangements for modifying reference values, feedback values or error values in the control loop of a converter
-
- 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
- H02M1/38—Means for preventing simultaneous conduction of switches
- H02M1/385—Means for preventing simultaneous conduction of switches with means for correcting output voltage deviations introduced by the dead time
-
- 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
- H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
- H02M7/42—Conversion of dc power input into ac power output without possibility of reversal
- H02M7/44—Conversion of dc power input into ac power output without possibility of reversal by static converters
- H02M7/48—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
- H02M7/53—Conversion of dc power input into ac power output without possibility of reversal 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
- H02M7/537—Conversion of dc power input into ac power output without possibility of reversal 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, e.g. single switched pulse inverters
- H02M7/5387—Conversion of dc power input into ac power output without possibility of reversal 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, e.g. single switched pulse inverters in a bridge configuration
- H02M7/53871—Conversion of dc power input into ac power output without possibility of reversal 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, e.g. single switched pulse inverters in a bridge configuration with automatic control of output voltage or current
-
- 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
- H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
- H02M7/42—Conversion of dc power input into ac power output without possibility of reversal
- H02M7/44—Conversion of dc power input into ac power output without possibility of reversal by static converters
- H02M7/48—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
- H02M7/53—Conversion of dc power input into ac power output without possibility of reversal 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
- H02M7/537—Conversion of dc power input into ac power output without possibility of reversal 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, e.g. single switched pulse inverters
- H02M7/539—Conversion of dc power input into ac power output without possibility of reversal 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, e.g. single switched pulse inverters with automatic control of output wave form or frequency
- H02M7/5395—Conversion of dc power input into ac power output without possibility of reversal 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, e.g. single switched pulse inverters with automatic control of output wave form or frequency by pulse-width modulation
Definitions
- the present disclosure relates to a power conversion device and a control method for the power conversion device.
- Hysteresis control is known as one technique for power converters, in which a semiconductor switching element (hereinafter simply referred to as a “switching element”) is turned on and off according to a comparison between a current or voltage to be controlled and a threshold.
- a semiconductor switching element hereinafter simply referred to as a “switching element”
- Patent Document 1 Japanese Patent Laying-Open No. 2005-341712
- one of the first and second thresholds is compared with a signal corresponding to the inductor current to determine the on/off timing of the switching element.
- a current hysteresis control is described.
- the first and second thresholds are set to have a central value based on the output voltage and a width corresponding to the target value of the switching frequency.
- it describes control of setting the switching frequency as a target value by changing the width of the hysteresis band corresponding to the difference between the first and second thresholds according to the output voltage.
- Patent Document 1 The hysteresis control of Patent Document 1 is applied to a power conversion device configured with single switching.
- a power conversion device having a plurality of switching elements that are connected in series between two electric wires and that constitute a so-called leg, when the two semiconductor switching elements that constitute the same leg are alternately turned on and off, , and dead time, during which both are turned off.
- the present disclosure has been made to solve such problems, and an object of the present disclosure is to stably control the switching frequency to a target value even when a dead time is provided. Another object is to provide hysteresis control of power converters where possible.
- a power conversion device includes a power conversion circuit and a control circuit.
- the power conversion circuit has first and second switching elements connected in series between first and second wires.
- the control circuit performs hysteresis control based on a comparison between a detected value of an electric quantity handled in power conversion by the power conversion circuit and an upper limit value and a lower limit value of a hysteresis band that includes the command value of the electric quantity. to control the on/off of the switching elements.
- the on/off of the first and second switching elements is controlled so as to provide a dead time during which both the first and second switching elements are turned off when on/off is switched.
- the control circuit includes a hysteresis band generation section, an upper/lower limit value setting section, a dead time compensation section, a hysteresis comparator, and a dead time generator.
- the upper/lower limit value setting unit sets the upper limit value and the lower limit value according to the hysteresis band width and the command value.
- the dead time compensator adds a compensation amount to the upper limit value and the lower limit value set by the upper and lower limit value setting unit to prevent the detected value from going out of the hysteresis band during the dead time.
- the hysteresis comparator compares the upper limit value and lower limit value after processing by the dead time compensator and the detected value.
- the dead time generator Based on the output signal of the hysteresis comparator, the dead time generator generates on/off control signals for the first and second switching elements so as to give dead time.
- the dead time compensator performs a process of adding compensation amounts of different polarities to different one of the upper limit value and the lower limit value depending on whether the detected value is positive or negative.
- a method for controlling a power converter includes a power conversion circuit having first and second switching elements connected in series between first and second wires, and turning on/off of the first and second switching elements Control is performed to provide a dead time during which both the first and second switching elements are turned off when switching.
- the control method is a hysteresis control based on a comparison between a detected value of an electric quantity handled in power conversion by the power conversion circuit and an upper limit value and a lower limit value of a hysteresis band containing the command value of the electric quantity, and the first and the first a step of controlling on/off of two switching elements;
- the step of controlling includes a step of generating a hysteresis band width in hysteresis control according to target values of switching frequencies of the first and second switching elements, and a step of setting upper and lower limits according to the hysteresis band width and the command value.
- dead time compensation for adding a compensation amount for preventing the detected value from going out of the hysteresis band during the dead time to the set upper and lower limit values; a step of operating a hysteresis comparator so as to compare the latter upper limit value and lower limit value with the detected value; and generating an on/off control signal.
- dead time compensation compensation amounts of different polarities are added to different upper and lower limit values depending on whether the detected value is positive or negative.
- a positive or negative compensation amount is selectively added to one of the upper and lower limits of the hysteresis band set according to the target value of the switching frequency. By doing so, it is possible to prevent the detection value from going out of the hysteresis band due to changes in the detection value during the dead time period. hysteresis control can be realized.
- FIG. 1 is a schematic configuration diagram of a power converter according to Embodiment 1;
- FIG. FIG. 5 is a functional block diagram illustrating hysteresis control according to a comparative example;
- FIG. 3 is an example of a waveform diagram of reactor current under hysteresis control in FIG. 2 ;
- FIG. 4 is a functional block diagram illustrating hysteresis control having a dead time imparting function; 5 is a signal waveform diagram for explaining the operation of the dead time generator shown in FIG. 4;
- FIG. FIG. 4 is a waveform diagram of reactor current for explaining the influence of dead time on hysteresis control;
- 3 is a functional block diagram illustrating hysteresis control according to Embodiment 1;
- FIG. 4 is a first control waveform example of reactor current for explaining hysteresis control according to Embodiment 1.
- FIG. 7 is a second control waveform example of reactor current for explaining hysteresis control according to Embodiment 1.
- FIG. 7 is a flowchart for explaining upper and lower limit setting processing for hysteresis control according to Embodiment 1;
- 4 is a functional block diagram illustrating hysteresis control according to a modification of Embodiment 1;
- FIG. 9 is a flowchart for explaining hysteresis control processing according to a modification of the first embodiment;
- 2 is a schematic configuration diagram of a power converter according to Embodiment 2;
- FIG. 9 is a functional block diagram illustrating hysteresis control according to Embodiment 2;
- FIG. 15 is a functional block diagram illustrating a configuration example of a neutral point voltage calculator shown in FIG. 14; 16 is a conceptual waveform diagram for explaining the operation of the leg voltage calculator shown in FIG. 15;
- FIG. 9 is a flowchart for explaining current comparison processing of hysteresis control according to Embodiment 2;
- Embodiment 1 (Example of circuit configuration) First, a configuration example of the power converter according to Embodiment 1 will be described.
- FIG. 1 shows a schematic configuration diagram of a power converter 100 according to the first embodiment.
- the power conversion device 100 is connected between the DC power supply 10 and the AC power supply 20 and performs power transmission between the DC power supply 10 and the AC power supply 20 .
- the AC power supply 20 is composed of three-phase AC, and the neutral point Nnw is grounded.
- the power conversion device 100 includes DC link capacitors 131 and 132 having equivalent capacitance values, a three-phase inverter circuit 120, current control reactors 141a to 141c having equivalent inductance values, and a control circuit 150. Power conversion (DC/AC conversion) is performed between the DC power supply 10 and the AC power supply 20 by the three-phase inverter circuit 120 .
- the three-phase inverter circuit 120 has a first leg 121 to a third leg 123 for three phases connected in parallel between the positive electrode wire 111 and the negative electrode wire 112 .
- the first leg 121 has switching elements Q1A and Q1B connected in series between the positive electrode wire 111 and the negative electrode wire 112 .
- the second leg 122 has switching elements Q2A and Q2B connected in series between the positive electrode wire 111 and the negative electrode wire 112 .
- third leg 123 has switching elements Q3A and Q3B connected in series between positive electrode wire 111 and negative electrode wire 112 .
- the first leg 121 is a series connection circuit of the switching element Q1A on the positive electrode side and the switching element Q1B on the negative electrode side.
- the second leg 122 is a series connection circuit of a positive-side switching element Q2A and a negative-side switching element Q2B.
- the third leg 123 is a series connection circuit of a positive electrode side switching element Q3A and a negative electrode side switching element Q3B.
- Each of the switching elements on the positive electrode side and the negative electrode side of the first leg 121 to the third leg 123 may be composed of a plurality of switching elements.
- Each switching element Q1A, Q1B, Q2A, Q2B, Q3A, Q3B has a semiconductor element capable of controlling the on and off timing, represented by IGBT (Insulated Gate Bipolar Transistor) or MOSFET (Metal Oxide Semiconductor Field Effect Transistor). Used.
- a diode 21 (hereinafter referred to as an antiparallel diode 21) is antiparallel connected to each of the switching elements Q1A, Q1B, Q2A, Q2B, Q3A, and Q3B.
- Each of the switching elements Q1A to Q3A on the positive electrode side corresponds to an embodiment of the "first switching element”
- each of the switching elements Q1B to Q3B on the negative electrode side corresponds to an embodiment of the "second switching element". do.
- the positive electric wire 111 and the negative electric wire 112 are connected to the positive and negative electrodes of the DC power supply 10, respectively.
- the DC link capacitors 131 and 132 are connected in series between the positive wire 111 and the negative wire 112 in parallel with the DC power supply 10 .
- the neutral point Nnp of the DC power supply 10 which is the connection point of the DC link capacitors 131 and 132, is grounded in the same way as the neutral point Nnw of the AC power supply 20 is. That is, in the example of FIG. 1, both the neutral point Nnp and the neutral point Nnw are grounded and have the same potential.
- the midpoint Na of the first leg 121 that is, the connection point between the switching elements Q1A and Q1B is connected to one terminal of the current control reactor 141a.
- the intermediate point Nb of the second leg 122 that is, the connection point of the switching elements Q2A and Q2B, is connected to one terminal of the current control reactor 141b
- the intermediate point Nc of the third leg 123 that is, the switching element Q3A. and Q3B is connected to one terminal of the current control reactor 141c.
- the ground potentials of intermediate points Na to Nc are expressed as voltages ua to uc.
- the other terminals of the current control reactors 141 a to 141 c are connected to each phase of the AC power supply 20 .
- the AC power supply 20 mainly operates as a voltage source having a-phase to c-phase AC voltage sources Ea to Ec, and power conversion between the DC power supply 10 and the AC power supply 20 by power conversion by the three-phase inverter circuit 120. is realized.
- current sensors 145a to 145c are provided for detecting reactor currents ia to ic of respective phases flowing into AC power supply 20 through current control reactors 141a to 141c, respectively.
- the AC power supply 20 is provided with voltage sensors (not shown) for detecting the voltages (AC) va to vc output to each phase.
- the voltages va to vc can be detected, for example, by arranging a voltage sensor (not shown) that detects ground potential. , may be converted into voltages va to vc indicating the ground potential in the control circuit 150 .
- Values detected by various sensors including the current sensors 145a to 145c and a voltage sensor (not shown) are input to the control circuit 150.
- the control circuit 150 outputs gate signals for controlling ON/OFF of each of the switching elements Q1A, Q1B, Q2A, Q2B, Q3A, and Q3B based on the input sensor detection values. Thereby, power conversion by the three-phase inverter circuit 120 is controlled.
- control circuit 150 is computer-based so as to include a CPU (Central Processing Unit) 155 , a memory 156 , and an input/output (I/O) circuit 157 .
- the CPU 155 , memory 156 and I/O circuit 157 can exchange data with each other via a bus 158 .
- a program is stored in advance in a partial area of the memory 156, and the CPU 155 can execute hysteresis control, which will be described later, by executing the program.
- the I/O circuit 157 inputs and outputs signals and data to/from the outside of the control circuit 150 (for example, a sensor group including the three-phase inverter circuit 120 and the current sensors 145a to 145c).
- control circuit 150 can be configured using a digital electronic circuit such as FPGA (Field Programmable Gate Array) or ASIC (Application Specific Integrated Circuit). is. Also, at least part of the control circuit 150 can be configured by analog electronic circuits including comparators, operational amplifiers, differential amplifier circuits, and the like. It is assumed that the function of each block constituting each of the plurality of hysteresis control units described below is realized by at least one of software processing and hardware processing by control circuit 150 .
- a digital electronic circuit such as FPGA (Field Programmable Gate Array) or ASIC (Application Specific Integrated Circuit).
- analog electronic circuits including comparators, operational amplifiers, differential amplifier circuits, and the like. It is assumed that the function of each block constituting each of the plurality of hysteresis control units described below is realized by at least one of software processing and hardware processing by control circuit 150 .
- hysteresis control for controlling the on/off of the switching elements Q1A and Q1B forming the first leg 121 based on the reactor current ia will be representatively described. However, for each hysteresis control described below, in each of the second leg 122 and the third leg 123, the switching elements Q2A and Q2B and the switching elements Q3A and Q3B are turned on and off based on the reactor currents ib and ic, respectively.
- a hysteresis control for controlling the can be implemented as well.
- FIG. 2 shows a functional block diagram for explaining hysteresis control according to a comparative example.
- the hysteresis control unit 30 a according to the comparative example has adders 52 and 54 , a hysteresis comparator 60 and an inverter 61 .
- the adder 52 adds the current command value ia* of the reactor current ia and (BW/2) to calculate the upper limit value Iup of the hysteresis band.
- the adder 54 adds the current command value ia* and -(BW/2) to calculate the lower limit value Ilw of the hysteresis band.
- the current command value ia* is a sinusoidal current having the same frequency as the three-phase AC voltage of AC power supply 20 .
- the hysteresis comparator 60 indicates a comparison result between the reactor current ia (detected value) detected by the current sensor 145a and the upper limit value Iup and the lower limit value Ilw of the hysteresis band. It outputs a pulse signal having a logic low level (“L level”).
- the output signal S1a* of the hysteresis comparator 60 is used as it is as the gate signal S1a of the switching element Q1A on the positive electrode side.
- the inverter 61 inverts the output signal of the hysteresis comparator 60 .
- S1b* obtained by inverting the output signal S1a* is used as the gate signal S1b of the switching element Q1B on the negative electrode side.
- the corresponding switching element is turned on during the H level period of each gate signal, and the corresponding switching element is turned off during the L level period.
- the gate signals S1a and S1b in FIG. 2 are gate signals for theoretical on/off control with no dead time.
- the positive side switching element Q1A and the negative side switching element Q1B are complementarily turned on and off in response to the gate signals S1a and S1b using S1a* and S1b* as they are.
- FIG. 3 shows an example of a reactor current waveform diagram by the hysteresis control of FIG.
- the output voltage of the three-phase inverter circuit 120 that is, the voltage of the DC power supply 10
- the potential (E/2) of the positive electrode wire 111 is the voltage va of the AC power supply 20. It is assumed that the potential of the a-phase is exceeded.
- the reactor current ia increases during the ON period of the switching element Q1A on the positive electrode side.
- the reactor current decreases during the ON period of the switching element Q1B on the negative electrode side (the OFF period of the switching element Q1A).
- the output signal of the hysteresis comparator 60 changes, thereby switching the switching element Q1A on the positive side and the switching element Q1A on the negative side.
- the ON periods of Q1B are provided alternately, and the direction of change in reactor current ia is reversed.
- time t1 is the ON period of the switching element Q1A on the positive electrode side
- the rising reactor current ia is compared with the upper limit value Iup, and the output signal of the hysteresis comparator 60 is maintained at the H level while ia ⁇ Iup. .
- the output signal of the hysteresis comparator 60 changes from H level to L level.
- the switching element Q1A on the positive electrode side is turned off and the switching element Q1B on the negative electrode side is turned on, so that the reactor current ia begins to decrease.
- the reactor current ia is compared with the lower limit value Ilw, and the output signal of the hysteresis comparator 60 is maintained at L level while ia>Ilw.
- the output signal of hysteresis comparator 60 changes from L level to H level.
- the switching element Q1B on the negative electrode side is turned off and the switching element Q1A on the positive electrode side is turned on, so that the reactor current ia starts to rise.
- the duty D is the ratio of the ON period length Ton of the switching element Q1A to the switching period Tsw.
- the ratio of the OFF period length Toff of the switching element Q1A (that is, the ON period of the switching element Q1B) to the switching period Tsw is given by (1 ⁇ D).
- FIG. 4 shows a functional block diagram of hysteresis control having a dead time imparting function.
- the hysteresis control section 30b shown in FIG. 4 further has a dead time generator 70 compared to the configuration of the hysteresis control section 30a shown in FIG.
- the dead time generator 70 receives the output signals S1a* and S1b* of the hysteresis comparator 60 and the inverter 61 and generates gate signals S1a and S1b to which dead time is added.
- FIG. 5 shows a signal waveform diagram for explaining the operation of the dead time generator 70.
- the output signal S1a* of the hysteresis comparator 60 and its inverted signal S1b* are alternately set to one of H level and L level.
- the dead time generator 70 generates a turn-off command at the same timing when the switching elements on the positive electrode side and the negative electrode side are turned on and off, and adds a predetermined delay time Td to the turn-on command. do.
- both the gate signals S1a and S1b are set to the L level, that is, a dead time can be provided in which an OFF command is given to both the switching elements on the positive electrode side and the sub-electrode side.
- the period length of the dead time is also simply referred to as dead time Td.
- FIG. 6 shows an example of a reactor current waveform diagram for explaining the effect of dead time on hysteresis control.
- FIG. 6 shows an example waveform of the reactor current when hysteresis control is performed using the gate signals S1a and S1b of FIG. be
- the gate signal S1a is maintained at L level from time t2 until the dead time Td elapses. Therefore, the reactor current ia continues to decrease during the dead time period. Then, at time t2x after the dead time Td has elapsed, the gate signal S1a changes from L level to H level, so that the reactor current ia turns to increase.
- the length of time until the reactor current ia reaches the upper limit value Iup increases from time t2 to time t3 in FIG. . Therefore, it is understood that the actual switching period Tsw under hysteresis control has an error due to the influence of the dead time with respect to the target value Ttrg corresponding to the hysteresis band width BW.
- Hysteresis control according to Embodiment 1 In the first embodiment, hysteresis control that compensates for the effects of dead time described above will be described.
- FIG. 7 is a functional block diagram illustrating hysteresis control according to Embodiment 1.
- FIG. Hysteresis controller 31 according to the first embodiment includes hysteresis band generator 50 , adders 52 and 54 , hysteresis comparator 60 , dead time generator 70 , and dead time compensators 72 and 74 . That is, the hysteresis control section 31 further includes a hysteresis band generation section 50 and dead time compensation sections 72 and 74, as compared with the hysteresis control section 30b shown in FIG.
- the hysteresis band generator 50 has the function of calculating the hysteresis band width BW for controlling the switching frequency to the target value ftrg, and also calculates the duty D, (1- It has the arithmetic function of D).
- the ON period length Ton and the OFF period length Toff of the switching element Q1A on the positive electrode side can be expressed by the following equations (2) and (3).
- the hysteresis band width BW for setting the switching frequency to the target value ftrg under the current slope of the reactor current ia is calculated from the equation (5). That is, the hysteresis band generation unit 50 calculates from the detected value of the voltage va, the voltage E (constant or detected value) of the DC power supply 10, the inductance value L of the current control reactor 141a, and the target value ftrg of the switching frequency. be done.
- the hysteresis band generation unit 50 inputs +(BW/2) to the adder 52 and -(BW/2) to the adder 54 based on the hysteresis band width BW calculated by Equation (5). input.
- the adders 52 and 54 correspond to one embodiment of the "upper/lower limit value setting unit", and the hysteresis band defined by the upper limit value Iup and the lower limit value Ilw can include the current command value ia*.
- the reactor current ia corresponds to an example of the "electrical quantity" subject to hysteresis control
- the current command value ia* corresponds to an example of the "command value" of the electric quantity. do.
- the dead time compensator 72 determines the dead time based on the upper limit value Iup (before dead time compensation) from the adder 52, the duty D generated by the hysteresis band generator 50, and the polarity (positive/negative) of the reactor current ia. An upper limit value Iupc after time compensation is generated.
- the dead time compensation unit 74 receives the lower limit value Ilw (before dead time compensation) from the adder 54, the duty (1 ⁇ D) generated by the hysteresis band generation unit 50, and the polarity (positive/negative) of the reactor current ia. to generate the lower limit value Ilwc after dead time compensation.
- the dead time compensation units 72, 72 use the current command value ia* to determine the polarity (positive/negative) of the reactor current ia, thereby stabilizing the positive/negative determination result.
- the hysteresis comparator 60 compares the upper limit value Iupc and lower limit value Ilwc of the hysteresis band after processing by the dead time compensators 72 and 74 with the reactor current ia (detected value) detected by the current sensor 145a.
- the output signal S1a* of the hysteresis comparator 60 and its inverted signal S1b* are input to the dead time generator 70, and the dead time generator 70 generates the gate signal S1a to which the dead time is added. , S1b. That is, the hysteresis control unit 31 of FIG. 7 uses the upper limit value Iupc and the lower limit value Ilwc of the hysteresis band after dead time compensation to control the gate signals S1a and S1b similarly to the hysteresis control unit 30b shown in FIG. It is generated.
- FIG. 6 exemplifies calculation of the compensation amount for the lower limit value Ilw for coping with the influence of dead time.
- the output signal (S1a*) of the hysteresis comparator 60 is Even when the level changes from the L level to the H level, the reactor current ia continues to decrease until time t2x when the dead time Td elapses.
- the ON period of the switching element Q1A for increasing the reactor current ia does not start, so the reactor current ia drops below the lower limit value Ilw by Xd. That is, a control error occurs in the reactor current ia with respect to the lower limit of the hysteresis band. In this way, if the reactor current behaves (increase/decrease) differently during the dead time and after the dead time ends, a control error will occur with respect to the upper or lower limit of the hysteresis band. Become.
- the slope of the reactor current ia is the same between times t1 to t2 and between times t2 to t2x. A proportional relationship is established.
- the gate signal S1a changes from the L level to the H level.
- the lower limit value of the reactor current ia at the changing timing can be controlled to the lower limit value Ilw (before compensation) based on the hysteresis band width BW.
- FIG. 8 shows an example of reactor current control waveforms when the reactor current ia is positive (ia>0).
- the reactor current ia When the reactor current ia is positive, on the lower limit side of the hysteresis band, the behavior (increase/decrease) of the reactor current ia differs during the dead time and during the ON period of the switching element Q1A after the dead time. As a result, a control error (Xd) of the reactor current ia as illustrated in FIG. 6 occurs during the dead time period. As a result, as indicated by the dotted line in FIG. 8, in the hysteresis control according to the upper limit value Iup and the lower limit value Ilw before compensation, the reactor current ia falls outside the hysteresis band on the lower limit side during the dead time period. I'm out.
- the reactor current ia decreases when both the switching elements Q1A and Q1B are turned off during the dead time Td. That is, the behavior of the reactor current ia is the same during the dead time and during the OFF period of the switching element Q1A (ON period of the switching element Q1B) after the dead time. Therefore, there is no need to compensate for the upper limit Iup according to the hysteresis band width BW calculated by the hysteresis band generator 50 .
- the dead time compensation unit 72 reduces the upper limit value Iup according to the hysteresis band width BW calculated by the hysteresis band generation unit 50 to
- the reactor current ia is outside the hysteresis band (hysteresis band width BW) during the dead time period by the hysteresis control using the lower limit value Ilwc compensated on the rising side. can avoid going out.
- FIG. 9 shows an example of reactor current control waveforms when the reactor current ia is negative (ia ⁇ 0).
- the reactor current ia When the reactor current ia is negative, the reactor current ia rises during the dead time period, contrary to FIG. Therefore, on the upper limit side of the hysteresis band, the behavior (increase/decrease) of the reactor current ia during the dead time differs from that during the OFF period of the switching element Q1A after the dead time. This causes a control error of the reactor current ia during the dead time period. As a result, as indicated by the dotted line in FIG. 9, in the hysteresis control according to the upper limit value Iup and the lower limit value Ilw before compensation, the reactor current ia falls outside the hysteresis band on the upper limit side during the dead time period. I'm out.
- the dead time compensation unit 72 reduces the upper limit value Iup according to the hysteresis band width BW calculated by the hysteresis band generation unit 50 to the negative value.
- the compensation amount Xd# at this time can be obtained by the following formula (10) by replacing the duty (1-D) with D in the formula (9).
- the dead time compensation unit 74 reduces the lower limit value Ilw according to the hysteresis band width BW calculated by the hysteresis band generation unit 50 to
- the reactor current ia is outside the hysteresis band (hysteresis band width BW) during the dead time period by the hysteresis control using the upper limit value Iupc compensated on the lower side. can avoid going out.
- the compensation amount Xd (Xd>0) or Xd# ( Xd# ⁇ 0) is added. That is, the polarity (positive/negative) of the compensation amount and to which of the upper limit value Iup and the lower limit value Ilw the compensation amount is added differ depending on whether the reactor current ia is positive or negative.
- the absolute values of the compensation amounts Xd and Xd# are proportional to the duties D and (1-D). It is understood that it is proportional to the ratio of the dead time Td to the ON period length of Q1B.
- FIG. 10 shows a flowchart for explaining processing for setting upper and lower limit values of hysteresis control according to the first embodiment.
- the control process of FIG. 10 is periodically and repeatedly executed by the control circuit 150 .
- step (hereinafter simply referred to as "S") 110 the control circuit 150 obtains the voltages va to vc from the sensor output and the current command values ia* to ic*.
- the control circuit 150 calculates the hysteresis band width BW according to the above equation (5) in S120, and calculates the duty D, (1-D) used in dead time compensation in S130.
- the duty can be calculated using, for example, formulas (6) and (7) described above, but can also be calculated using other methods.
- the duty D, (1 ⁇ D) there It is also possible to calculate from the ratio.
- the processing from S120 to S130 corresponds to the operation of the hysteresis band generator 50 in FIG.
- the control circuit 150 calculates the upper limit value Iup and lower limit value Ilw of the hysteresis band for each phase based on the hysteresis band width BW and the current command values ia* to ic* calculated at S120.
- the processing by S140 corresponds to the output operation of BW/2 and -(BW/2) from the hysteresis band generator 50 and the operations of the adders 52 and 54.
- control circuit 150 calculates the upper limit value Iupc and the lower limit value Ilwc of the hysteresis band after dead time compensation.
- S150 includes S152, S154, and S156.
- the control circuit 150 determines the polarity (positive/negative) of the reactor currents ia to ic in each phase based on the current command values ia* to ic*. If the reactor current is positive (YES determination in S152), the process proceeds to S154, and if the reactor current is negative (NO determination in S152), the process proceeds to S156.
- Dead time compensation is performed so as to decrease.
- the processing of S150 corresponds to the operation of dead time compensators 72 and 74 in FIG.
- the upper limit value Iupc and lower limit value Ilwc of the hysteresis band set by the control process of FIG. A gate signal for the switching element of each leg to which a dead time Td is added is generated so as to hysteresis-control the value (instantaneous value).
- a positive or negative compensation amount is selectively added to one of the upper limit value and the lower limit value of the hysteresis band set according to the target value of the switching frequency.
- Embodiment 1 is a functional block diagram illustrating hysteresis control according to a modification of Embodiment 1.
- FIG. 11 is a functional block diagram illustrating hysteresis control according to a modification of Embodiment 1.
- the hysteresis control unit 32 according to the modification of the first embodiment further includes a protection circuit 80 compared to the hysteresis control unit 31 (FIG. 7) according to the first embodiment. different.
- the limit value BWmin can be determined in advance based on the slope of the reactor current ia, which depends on the inductance value of the current control reactor 141a, so as not to destabilize the switching operation.
- the hysteresis comparator adds (BWmin-BW#)/2 to the upper limit value Iupc and subtracts (BWmin-BW#)/2 from the lower limit value Ilwc.
- 60 input upper and lower hysteresis band values Iupc and Ilwc (after dead time compensation) can be modified.
- FIG. 11 Another configurations of FIG. 11 are the same as those of hysteresis control unit 31 of FIG. 7, and thus detailed description thereof will not be repeated.
- FIG. 12 shows a flowchart for explaining the hysteresis control process according to the modification of the first embodiment.
- control circuit 150 executes the processing of S160 for protecting the hysteresis bandwidth after S110-S150 as in FIG. S160 includes S162, S164, and S166.
- the control circuit 150 compares the hysteresis band width BW# based on the upper limit value Iupc and the lower limit value Ilwc after processing by the dead time compensation units 72 and 74 with a predetermined limit value BWmin. If BW# ⁇ BWmin (YES determination in S162), the process proceeds to S164, and if BW# ⁇ BWmin (NO determination in S162), the process proceeds to S166.
- the control circuit 150 corrects the upper limit value Iupc and lower limit value Ilwc of the hysteresis band input to the hysteresis comparator 60 so that BW# ⁇ BWmin is ensured.
- the upper limit value Iupc and the lower limit value Ilwc can be corrected such that the upper limit value Iupc is increased and the lower limit value Ilwc is decreased.
- control circuit 150 inputs the upper limit value Iupc and the lower limit value Ilwc after processing by the dead time compensators 72 and 74 to the hysteresis comparator 60 without correcting them.
- the processing of S160 corresponds to the operation of the protection circuit 80 in FIG.
- the switching operation can be stabilized by maintaining the hysteresis width at or above a certain level.
- FIG. 13 is a schematic configuration diagram of a power conversion device 101 according to Embodiment 2. As shown in FIG. 13
- the power converter 101 shown in FIG. 13 is similar to that of the first embodiment in that the neutral point Nnp on the DC side of the three-phase inverter circuit 120 (that is, the neutral point of the DC power supply 10) is not grounded. It differs from the power conversion device 100 .
- Other configurations of power converter 101 are the same as those of power converter 100, and detailed description thereof will not be repeated.
- neutral point voltage vnp the potential difference between the neutral point Nnw on the AC side and the neutral point Nnp on the DC side.
- neutral point voltage vnp the neutral point voltage
- the amount of current fluctuation due to such fluctuations in the neutral point voltage affects the hysteresis control that controls the reactor current, so if the neutral point voltage fluctuates, it is necessary to remove the amount of current fluctuation due to this. .
- the neutral point Nnw on the AC side is grounded, while the neutral point Nnp on the DC side is not grounded. It occurs because the point Nnp or the neutral point Nnw is not grounded.
- the neutral point Nnp of the DC power supply 10 corresponds to one embodiment of the "first neutral point”
- the neutral point Nnw of the AC power supply 20 corresponds to one embodiment of the "second neutral point”. handle.
- FIG. 14 shows a functional block diagram for explaining hysteresis control according to the second embodiment.
- the hysteresis control unit 33 reduces the neutral point voltage fluctuation of the reactor current ia by It differs in that it further has a current compensator 90 for removing it.
- the configuration of other parts of the hysteresis control unit 33 is the same as that of the hysteresis control unit 31, and will not be repeated.
- a protection circuit 80 similar to that shown in FIG. Accordingly, in the hysteresis control unit 33 as well, the upper limit value Iupc and the lower limit value Ilwc of the hysteresis band input to the hysteresis comparator 60 are calculated in the same manner as in the first embodiment or its modification.
- the current compensator 90 has a neutral point voltage calculator 92 , a current fluctuation component calculator 95 , and a subtractor 98 .
- a neutral point voltage calculator 92 calculates a neutral point voltage Vnp corresponding to a theoretical value of the neutral point voltage vnp from the switching patterns of the switching elements Q1A to Q3A and Q1B to Q3B.
- the neutral point voltage Vnp has a stepped voltage waveform that changes according to the switching pattern.
- Vnp +(E/6).
- Vnp +(E/2) during the period when all three switching elements on the positive electrode side are on
- Vnp -(E/2) during the period when all three switching elements on the negative electrode side are on. 2).
- the neutral point voltage Vnp is determined by a combination of voltages ua to uc, which are ground potentials of intermediate points Na to Nc of the first leg 121 to the third leg 123 .
- the theoretical values of the voltages ua to uc determined by the switching pattern in each leg are hereinafter also referred to as leg voltages Ua* to Uc*.
- FIG. 15 shows a configuration example of the neutral point voltage calculator 92 shown in FIG.
- the neutral point voltage calculator 92 has leg voltage calculators 93 a to 93 c and a Vnp calculator 94 .
- Leg voltage calculator 93a calculates leg voltage Ua*, which is the theoretical value of ground potential at midpoint Na of first leg 121, using gate signals S1a and S1b of switching elements Q1A and Q1B and reactor current ia. do.
- FIG. 16 shows a conceptual waveform diagram for explaining the operation of the leg voltage calculator 93a of the first leg 121.
- leg voltage Ua* +(E/2).
- the antiparallel diode 21 of the switching element Q1A or Q1B conducts, thereby electrically connecting the intermediate point Na to the positive wire 111 or the negative wire 112. be done. Therefore, the leg voltage Ua* differs depending on the polarity (positive/negative) of the reactor current ia.
- the leg voltage calculator 93a can calculate the leg voltage Ua* based on the gate signals S1a and S1b of the switching elements Q1A and Q1B and the reactor current ia (polarity).
- leg voltage calculator 93b calculates the ground potential (theoretical value ) is calculated.
- the leg voltage calculator 93c uses the gate signals S3a and S3b of the switching elements Q3A and Q3B and the reactor current ic to calculate the leg voltage, which is the ground potential (theoretical value) of the intermediate point Nc of the third leg 123. Calculate Uc*.
- the gate signal S1a is replaced with the gate signal S2a or S3a
- the gate signal S1b is replaced with the gate signal S2b or S3b
- the reactor current ia is replaced with the reactor current ib or ic
- the leg voltage Ub* or Uc* can be obtained instead of the leg voltage Ua*.
- the Vpn calculator 94 calculates the neutral point voltage Vnp using the leg voltages Ua* to Uc* from the leg voltage calculators 93a to 93c. If the neutral point Nnp on the DC side is not grounded, no current path is formed via the neutral points Nnp and Nnw. , and changes stepwise as described above. A zero-phase current is added to each of the reactor currents ia to ic, and the sum of the reactor currents ia to ic after addition of the zero-phase currents becomes zero.
- the current fluctuation component calculation unit 95 calculates the current fluctuation component i0 caused by the change in the neutral point voltage Vnp. calculate.
- the subtractor 98 subtracts the current fluctuation component i0 calculated by the current fluctuation component calculator 95 from the detected value of the reactor current ia.
- a reactor current iac with the fluctuation component canceled is output.
- Reactor current iac from subtractor 98 is input to hysteresis comparator 60 .
- the hysteresis comparator 60 compares the reactor current iac compensated by the current compensation unit 90 with the upper limit value Iupc and the lower limit value Ilwc of the hysteresis band.
- hysteresis control of the reactor current can be performed similarly to the modification thereof.
- the current fluctuation component calculator 95 can be composed of integral elements having a time constant according to the inductance value L of the current control reactors 141a to 141c.
- the current fluctuation component calculation unit 95 further adds a high-pass filter (preferably, a second-order or higher-order high-pass filter) having a cutoff frequency sufficiently lower than the switching frequency in order to prevent the DC error from accumulating. It is also possible to calculate the current fluctuation component i0 by inputting the output value of to the integral element described above.
- the current fluctuation component calculator 95 can be configured using a first-order low-pass filter instead of the integral element described above.
- FIG. 17 shows a flowchart for explaining current comparison processing of hysteresis control according to the second embodiment.
- the control process of FIG. 17 is periodically and repeatedly executed by the control circuit 150 .
- the control circuit 150 acquires the upper limit value Iupc and the lower limit value Ilwc of the hysteresis band through S210.
- the processing of S210 is implemented by reading the values obtained by the control processing shown in FIG. 10 or 12 .
- control circuit 150 When the control circuit 150 acquires the reactor current detection values (ia to ic) from the sensor output in S220, the control circuit 150 removes the fluctuation component due to the neutral point potential fluctuation from the reactor current detection values in S230.
- S230 has S232 and S234.
- control circuit 150 calculates the current fluctuation component caused by the fluctuation of the neutral point voltage Vnp, and in S234 cancels the current fluctuation component obtained in S232 from the reactor current detection value (S220).
- the process of S232 corresponds to the operations of the neutral point voltage calculator 92 and the current fluctuation component calculator 95 in FIG. 14, and the process of S234 corresponds to the operation of the subtractor 98 in FIG.
- the control circuit 150 performs a process of comparing the reactor current (S234) with the upper limit value Iupc and the lower limit value Ilwc (S210) through S250 to S290. In S250, the control circuit 150 branches the processing according to the level of the output signal (corresponding to the output signal of the hysteresis comparator 60) indicating the comparison result.
- the control circuit 150 compares the output signal with the lower limit value Ilwc of the hysteresis band in S260 when the output signal is at the L level (when determined as YES in S250). While the reactor current is higher than the lower limit value Ilwc (NO determination in S260), S290 maintains the output signal at L level. On the other hand, when the reactor current drops to the lower limit value Ilwc (YES in S260), the output signal is inverted from the L level to the H level through S280.
- the control circuit 150 compares the reactor current with the upper limit value Iupc in S270. While the reactor current is lower than the upper limit value Iupc (NO determination in S270), the output signal is maintained at the H level by S290. On the other hand, when the reactor current rises to the upper limit value Iupc (YES in S270), the output signal is inverted from H level to L level in S280.
- the processing of S250-S290 corresponds to the operation of the hysteresis comparator 60 in FIG.
- the control circuit 150 generates a gate signal for each switching element of the three-phase inverter circuit 120 in S300, based on the output signal of the hysteresis comparator 60 obtained in S250-S290, in such a manner as to add dead time.
- the processing of S300 corresponds to the operation of the dead time generator 70.
- control circuit 150 can execute the hysteresis control current comparison process according to the first embodiment and its modification by the control process in which S230 is deleted from the flowchart shown in FIG.
- the reactor current detection value (S210) is compared with the upper limit value Iupc and the lower limit value Ilwc (S210).
- the processing of S250-S290 corresponds to the operation of the hysteresis comparator 60 of FIGS. 7 and 11, respectively.
- the neutral point potential fluctuates because the neutral point Nnw of the AC power supply 20 or the neutral point Nnp on the DC side of the three-phase inverter circuit 120 is not grounded.
- the effect of the hysteresis control according to Embodiment 1 or its modification can be obtained also in the configuration.
- the effect of dead time is eliminated, and the switching element is turned on and off according to the hysteresis band width BW reflecting the target value ftrg of the switching frequency. Therefore, the switching frequency can be stably controlled to the target value ftrg.
- the target value ftrg By setting the target value ftrg to a constant value as mentioned in the present embodiment, fluctuations in the switching frequency can be suppressed and the operation of the power converter can be stabilized. By stabilizing the switching frequency, it is possible to prevent an increase in the computational load on the microcomputer, FGPA, or the like that constitutes the control circuit 150 as the switching frequency increases.
- the switching frequency target value ftrg may be set variably according to the passage of time. For example, by changing the target value ftrg at regular time intervals, it is possible to operate the power converter so as to reduce the noise level peaks on the frequency spectrum. Moreover, it is possible to set the target value ftrg so as to reduce the noise level of a specific frequency in cooperation with an external device of the power converter.
- the target value ftrg of the switching frequency is variably set according to the temperature condition of the power converter.
- the amount of heat generated by the current control reactors 141a to 141c depends on the magnitude of the ripple current components of the reactor currents ia to ic, that is, the switching frequency of the three-phase inverter circuit 120. Therefore, the switching elements Q1A to Q3A and Q1B to Q3B and the temperatures of the current control reactors 141a to 141c, it is possible to change the target value ftrg.
- hysteresis control is applied to a three-phase inverter circuit.
- the hysteresis control according to the present embodiment is applied to a single-phase inverter circuit having two legs, a chopper circuit that performs DC/DC conversion, or a PWM rectifier circuit that performs AC/DC conversion. It is possible to
- the reactor currents ia to ic output from the three-phase inverter circuit 120 are subjected to hysteresis control.
- the hysteresis control according to the present embodiment is realized by comparing the upper and lower limits of the hysteresis band that includes the command value of the electric quantity. It is possible.
- the quantity of electricity handled in power conversion which is the target of hysteresis control, is applied to the power converter such as the reactor current and the DC link voltage (the voltage of the DC link capacitors 131 and 132) in this embodiment. It includes the amount of electricity input and output and the amount of electricity detected inside the power converter.
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Abstract
Description
(回路構成例)
まず、実施の形態1に係る電力変換装置の構成例を説明する。
次に、制御回路150によって実行されるヒステリシス制御について説明する。まず、図2~図6を用いて、デッドタイムを考慮していない、比較例に係るヒステリシス制御を説明する。
比較例に係るヒステリシス制御部30aは、加算器52,54と、ヒステリシスコンパレータ60と、インバータ61とを有する。
図4には、デッドタイムの付与機能を有するヒステリシス制御の機能ブロック図が示される。
図5に示される様に、ヒステリシスコンパレータ60の出力信号S1a*及びその反転信号S1b*は、交互に、Hレベル及びLレベルの一方ずつに設定される。
実施の形態1では、上述したデッドタイムの影響を補償したヒステリシス制御について説明する。
実施の形態1に係るヒステリシス制御部31は、ヒステリシスバンド生成部50と、加算器52,54と、ヒステリシスコンパレータ60と、デッドタイム生成器70と、デッドタイム補償部72,74とを有する。即ち、ヒステリシス制御部31は、図4に示されたヒステリシス制御部30bと比較すると、ヒステリシスバンド生成部50と、デッドタイム補償部72,74とを更に有する。
図3に示されたリアクトル電流iaの傾き(dia/dt)は、電流制御リアクトル141aのインダクタンス値L、電圧va、及び、第1レグ121の中間点の電圧uaを用いて、下記の式(1)で求めることができる。
式(1)中において、電圧uaは、正極側のスイッチング素子Q1Aのオン期間では、ua=(E/2)であり、負極側のスイッチング素子Q1Bのオン期間では、ua=-(E/2)である。
Toff=BW・L/((E/2)-va) …(3)
従って、スイッチング周期Tswは、下記の式(4)で示される。
式(4)において、Tsw=Ttrg=1/ftrgを代入して、ヒステリシスバンド幅BWについて解くと、式(5)が得られる。
式(5)により、現在のリアクトル電流iaの傾きの下での、スイッチング周波数を目標値ftrgとするためのヒステリシスバンド幅BWが算出される。即ち、ヒステリシスバンド生成部50は、電圧vaの検出値、直流電源10の電圧E(定数、又は、検出値)、及び、電流制御リアクトル141aのインダクタンス値Lと、スイッチング周波数の目標値ftrgから算出される。
1-D=((E/2)+va)/E …(7)
ヒステリシスバンド生成部50は、式(5)で算出されたヒステリシスバンド幅BWを基に、加算器52に+(BW/2)を入力する一方で、加算器54に-(BW/2)を入力する。
式(8)中に、デッドタイム直前でのスイッチング素子Q1Bのオン期間長、即ち、スイッチング素子Q1Aのオフ期間長Toff=(1-D)・Tswを代入して、式(8)をXdについて解くと、下記の式(9)が得られる。
従って、図6の例では、下限値Ilxに対して、当該Xdを補償量として、デッドタイム補償後の下限値Ilwc=Ilw+Xdに設定することができる。これにより、補償後の下限値Ilwcに基づいてヒステリシスコンパレータ60の出力信号(S1a*)がLレベルからHレベルが変化してからデッドタイムTd経過後において、ゲート信号S1aがLレベルからHレベルに変化するタイミングにおけるリアクトル電流iaの下限値を、ヒステリシスバンド幅BWに基づく下限値Ilw(補償前)に制御することができる。
一方で、ヒステリシスバンドの下限値側では、デッドタイム中と、デッドタイム終了後のスイッチング素子Q1Aのオン期間との間で、リアクトル電流iaの挙動は同じである。従って、ヒステリシスバンド生成部50によって算出されたヒステリシスバンド幅BWに従う下限値Ilwについては補償する必要がない。
図11は、実施の形態1の変形例に係るヒステリシス制御を説明する機能ブロック図である。
図13は、実施の形態2に係る電力変換装置101の概略構成図である。
中性点電圧演算部92は、レグ電圧算出部93a~93cと、Vnp算出部94とを有する。
Claims (11)
- 第1及び第2の電線の間に直列接続された第1及び第2のスイッチング素子を有する電力変換回路と、
前記電力変換回路による電力変換で取り扱われる電気量の検出値と、当該電気量の指令値を包含するヒステリシスバンドの上限値及び下限値との比較に基づくヒステリシス制御によって前記第1及び第2のスイッチング素子のオンオフを制御する制御回路とを備え、
前記第1及び第2のスイッチング素子のオンオフは、オンオフが切替わる際に前記第1及び第2のスイッチング素子の両方がオフするデッドタイムが設けられる様に制御され、
前記第1及び第2のスイッチング素子のスイッチング周波数の目標値に従って、前記ヒステリシス制御におけるヒステリシスバンド幅を生成するヒステリシスバンド生成部と、
前記ヒステリシスバンド幅及び前記指令値に従って、前記上限値及び前記下限値を設定する上下限値設定部と、
前記上下限値設定部によって設定された前記上限値及び前記下限値に対して、前記デッドタイムの間に前記検出値が前記ヒステリシスバンドの外に出ることを避けるための補償量を加算するためのデッドタイム補償部と、
前記デッドタイム補償部による処理後の前記上限値及び前記下限値と、前記検出値とを比較するヒステリシスコンパレータと、
前記ヒステリシスコンパレータの出力信号に基づき、前記デッドタイムが付与される様に前記第1及び第2のスイッチング素子のオンオフの制御信号を生成するデッドタイム生成器とを含み、
前記デッドタイム補償部は、前記検出値が正の場合と負の場合との間で、前記上限値及び前記下限値の異なる一方に対して、異なる極性の前記補償量を加算する処理を実行する、電力変換装置。 - 前記デッドタイム補償部は、前記検出値が正である場合には、前記下限値を上昇する様に正の前記補償量を設定する一方で、前記検出値が負である場合には、前記上限値を低下する様に負の前記補償量を設定する、請求項1記載の電力変換装置。
- 前記デッドタイム補償部は、前記第1及び第2のスイッチング素子のスイッチング周期に対する前記第1及び第2のスイッチング素子のオン期間の比に応じて前記補償量を変化させる、請求項1又は2に記載の電力変換装置。
- 前記補償量の絶対値は、前記デッドタイムの直前でオンされていた前記第1又は第2のスイッチング素子のオン期間長に対する、前記デッドタイムの時間長の比に比例する様に設定される、請求項1~3のいずれか1項に記載の電力変換装置。
- 前記制御回路は、
前記デッドタイム補償部による処理後の前記上限値及び前記下限値の差分が予め定められた制限値より小さくなることを防止するための保護回路を更に含み、
前記保護回路は、前記差分が前記制限値よりも小さいときに、当該制限値が確保される様に、前記ヒステリシスコンパレータで用いられる前記上限値及び前記下限値を修正する、請求項1~4のいずれか1項に記載の電力変換装置。 - 前記電力変換回路は、前記第1及び第2のスイッチング素子で構成されたレグを複数個有し、かつ、前記第1及び第2の電線と接続された正極及び負極を有する直流電圧源と、各前記レグと接続された交流電圧源との間で電力変換を行う様に構成され、
前記電力変換装置は、
各前記レグの前記第1及び第2のスイッチング素子の接続点と、前記交流電圧源との間に接続されたリアクトルを更に備え、
前記検出値は、前記リアクトルを通過する電流検出値である、請求項1~5のいずれか1項に記載の電力変換装置。 - 前記直流電圧源の第1の中性点、及び、前記交流電圧源の第2の中性点の少なくとも一方が接地されておらず、
前記制御回路は、
前記第1及び第2の中性点の電位差である中性点電圧の変化による前記電流検出値の変動成分をキャンセルするための電流補償部を更に有し、
前記ヒステリシスコンパレータは、前記デッドタイム補償部による処理後の前記上限値及び前記下限値と、前記電流補償部によって前記変動成分が除去された前記電流検出値とを比較する、請求項6記載の電力変換装置。 - 第1及び第2の電線の間に直列接続された第1及び第2のスイッチング素子を有する電力変換回路を備えるとともに、前記第1及び第2のスイッチング素子のオンオフが、オンオフが切替わる際に前記第1及び第2のスイッチング素子の両方がオフするデッドタイムが設けられる様に制御される電力変換装置の制御方法であって、
前記電力変換回路による電力変換で取り扱われる電気量の検出値と、当該電気量の指令値を包含するヒステリシスバンドの上限値及び下限値との比較に基づくヒステリシス制御によって前記第1及び第2のスイッチング素子のオンオフを制御するステップを備え、
前記制御するステップは、
前記第1及び第2のスイッチング素子のスイッチング周波数の目標値に従って、前記ヒステリシス制御におけるヒステリシスバンド幅を生成するステップと、
前記ヒステリシスバンド幅及び前記指令値に従って、前記上限値及び前記下限値を設定するステップと、
設定された前記上限値及び前記下限値に対して、前記デッドタイムの間に前記検出値が前記ヒステリシスバンドの外に出ることを避けるための補償量を加算するデッドタイム補償を実行するステップと、
前記デッドタイム補償の後の前記上限値及び前記下限値と、前記検出値とを比較する様にヒステリシスコンパレータを動作させるステップと、
前記ヒステリシスコンパレータの出力信号に基づき、前記デッドタイムが付与される様に前記第1及び第2のスイッチング素子のオンオフの制御信号を生成するステップとを含み、
前記デッドタイム補償において、前記検出値が正の場合と負の場合とでは、前記上限値及び前記下限値の異なる一方に対して、異なる極性の前記補償量が加算される、電力変換装置の制御方法。 - 前記デッドタイム補償の後における前記上限値及び前記下限値の差分が予め定められた制限値より小さくなることを防止するステップを更に含み、
前記防止するステップでは、前記差分が前記制限値よりも小さいときに、当該制限値が確保される様に、前記ヒステリシスコンパレータで用いられる前記上限値及び前記下限値が修正される、請求項8記載の電力変換装置の制御方法。 - 前記電力変換回路は、前記第1及び第2のスイッチング素子で構成されたレグを複数個有し、かつ、前記第1及び第2の電線と接続された正極及び負極を有する直流電圧源と、各前記レグと接続された交流電圧源との間で電力変換を行う様に構成され、
前記電力変換装置は、
各前記レグの前記第1及び第2のスイッチング素子の接続点と、前記交流電圧源との間に接続されたリアクトルを更に備え、
前記検出値は、前記リアクトルを通過する電流検出値である、請求項8又は9に記載の電力変換装置の制御方法。 - 前記直流電圧源の第1の中性点、及び、前記交流電圧源の第2の中性点の少なくとも一方が接地されておらず、
前記制御するステップは、
前記第1及び第2の中性点の電位差である中性点電圧の変化による前記電流検出値の変動成分をキャンセルするステップを更に含み、
前記ヒステリシスコンパレータは、前記デッドタイム補償の後の前記上限値及び前記下限値と、前記キャンセルするステップによって前記変動成分が除去された前記電流検出値とを比較する、請求項10記載の電力変換装置の制御方法。
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JPH10225142A (ja) * | 1997-02-06 | 1998-08-21 | Fuji Electric Co Ltd | インバータのデッドタイム補償回路 |
JP2005341712A (ja) | 2004-05-27 | 2005-12-08 | Taiyo Yuden Co Ltd | 電源装置 |
JP2010088266A (ja) * | 2008-10-02 | 2010-04-15 | Omron Corp | 電圧型インバータのスイッチング信号生成方法及び装置 |
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JPH0947064A (ja) * | 1995-07-28 | 1997-02-14 | Matsushita Electric Works Ltd | インバータのデッドタイム補償方法 |
JPH10225142A (ja) * | 1997-02-06 | 1998-08-21 | Fuji Electric Co Ltd | インバータのデッドタイム補償回路 |
JP2005341712A (ja) | 2004-05-27 | 2005-12-08 | Taiyo Yuden Co Ltd | 電源装置 |
JP2010088266A (ja) * | 2008-10-02 | 2010-04-15 | Omron Corp | 電圧型インバータのスイッチング信号生成方法及び装置 |
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