Power converter control device

Abstract

Provided is a power converter control device that has a simple structure and can control a plurality of power converters to control the balance of their input voltages.　A power converter control device according to the present invention comprises a plurality of power converters (10), and a control unit (20) that feedback-controls the power converters (10). The control unit (20) corrects the on-time of the plurality of power converters (10) according to the reference voltage based on the input voltages to the plurality of power converters (10).

Description

[Technical Field]

[0001] The present invention relates to a power converter control device that controls multiple power converters. [Background technology]

[0002] Conventionally, when controlling multiple connected power converters, each power converter was equipped with a feedback control circuit, and individual feedback control was performed on each power converter by this feedback control circuit.

[0003] Non-Patent Document 1 is a prior art document that describes a method for controlling multiple connected power converters. Non-patent document 1 describes high input voltage auxiliary power supplies aimed at cost reduction. The method employed by these high input voltage auxiliary power supplies is based on a converter with input series and output parallel connections. The main output voltage is controlled by a master converter, while the input voltage and output current are controlled by slave converters to balance the connected converters.

[0004] Furthermore, configurations without a control unit are also known. For example, Figure 7 shows the configuration of a 2-series input-2-series output converter without a control unit. In the configuration shown in Figure 7, two power converters are connected in series on the input side and in series and parallel on the output side.

[0005] Each power converter has a first power MOSFETQ 11 ,S 21 And, the second power MOSFETQ 12 ,Q 22 Each is equipped with the first power MOSFETQ 11 ,S 21 The first gate voltage signal S gs11 ,S gs21is input, and the second power MOSFET Q 12 , Q 22 is input with the second gate voltage signal S ga21 , S gs22 . There is no problem if the first gate voltage signal S input to the first power MOSFET Q 11 of one power converter is not delayed relative to the first gate voltage signal S input to the first power MOSFET Q gs11 of the other power converter, but when a delay occurs, the situation is as shown in FIG. 8. 21 input to the first power MOSFET Q gs21 of the other power converter is not delayed relative to that, but when a delay occurs, the situation is as shown in FIG. 8. Here, let V in = 1500 V. In FIG. 8, there are shown the input voltage V in1 , input current V in1 , input-side transformer voltage V tr1 of one power converter, and the input voltage V in2 , input current V in2 , input-side transformer voltage V tr2 of the other power converter.

[0006] As shown in FIG. 8(A), when the turn-off time of S gs21 is delayed by 0.1 μs relative to S gs11 , it can be seen that with V in1 = 768 V and V in2 = 733 V, the balance of input voltages is about to be broken due to the difference in on-time. Further, as shown in FIG. 8(B), when the turn-off time of S gs21 is delayed by 1 μs relative to S gs11 , it can be seen that with V in1 = 906 V and V in2 = 594 V, the balance of input voltages is greatly broken. As described above, the balance of input voltages deteriorates more in proportion to an increase in the difference in on-time of gate signals. [Prior Art Literature] [Non-Patent Literature]

[0007] [Non-Patent Literature 1] Petar J. Grbovi´c, Master / Slave Control of Input-Series- and Output-Parallel-Connected Converters: Concept for Low-Cost High-Voltage Auxiliary Power Supplies, IEEE TRANSACTIONS ON POWER ELECTRONICS, VOL. 24, NO. 2, FEBRUARY 2009, pp. 316-327, 2009. [Overview of the Initiative] [Problems that the invention aims to solve]

[0008] When a feedback control circuit is not provided, the balance of the input voltage tends to deteriorate. Therefore, when control is performed using a master converter and a slave converter, as in the method described in Non-Patent Document 1, the control becomes complex because the input current is used during this control, and there is a problem in that detecting the input current is difficult.

[0009] Therefore, the present invention aims to provide a power converter control device that can control the balance of the input voltages of multiple power converters connected in series, with a simpler structure. [Means for solving the problem]

[0010] The power converter control device of the present invention includes a plurality of power converters and a control unit that provides feedback control of the power converters, and further includes a control unit that corrects the on-time of the plurality of power converters based on a reference voltage derived from the input voltages of the plurality of power converters.

[0011] Furthermore, if the power converter control device has only one control unit, it is preferable that the control unit is configured to correct the on-time of multiple power converters so that all of the multiple power converters receive the same input voltage.

[0012] Furthermore, if the power converter control device has two or more control units but fewer than the number of power converters, it is preferable that the two or more control units are configured to correct the on-time of the multiple power converters using the average value of the on-time when each of the two or more control units corrects a power converter individually.

[0013] Furthermore, when the control unit corrects the on-time of multiple power converters, it is preferable that the control unit is configured to correct the on-time by comparing the input voltage of a reference power converter with the input voltage of other power converters one by one, or by repeatedly processing and comparing the input voltage of a reference power converter with the input voltage of other power converters in parallel at once.

[0014] Alternatively, it is preferable that the control unit uses a comparator to determine the difference between the input voltage of a reference power converter and the input voltage of another power converter, and then uses a counter to correct the on-width and off-width of the input voltage of the other power converter based on this difference. [Effects of the Invention]

[0015] The power converter control device of the present invention includes a plurality of power converters and a control unit that provides feedback control of the power converters, and a control unit that corrects the on-time of the plurality of power converters based on a reference voltage derived from the input voltages of the plurality of power converters. By calculating a reference voltage based on the input voltage of each converter, which is easy to detect, and correcting the on-time using the reference voltage, the balance of the input voltages of a plurality of power converters connected in series can be controlled with a simple structure. [Brief explanation of the drawing]

[0016] [Figure 1] Figure 1 is a diagram illustrating the configuration of a power converter control device according to an embodiment of the present invention. [Figure 2] Figure 2 is a diagram illustrating the configuration of a power converter control device according to another embodiment of the present invention. [Figure 3] Figure 3 is a diagram illustrating the configuration of a control unit according to an embodiment of the present invention. [Figure 4] Figure 4 is a diagram illustrating the configuration of a control unit according to an embodiment of the present invention. [Figure 5] Figure 5 is a diagram illustrating the control method of the control unit. [Figure 6] Figure 6 shows the simulation results of a power converter control device according to an embodiment of the present invention. [Figure 7] Figure 7 shows the configuration of a conventional 2-series input-2-series output converter without a control unit. [Figure 8] Figure 8 shows an example of what happens when the input voltage balance is disrupted. [Modes for carrying out the invention]

[0017] The embodiments of the present invention will be described in detail below, but the description of the configuration below is just one example (representative example) of the embodiments of the present invention, and the present invention is not limited to the following unless its essence is changed.

[0018] [Power converter control device] Figure 1 is a diagram illustrating the configuration of a power converter control device according to an embodiment of the present invention. As shown in Figure 1, the power converter control device 1 consists of a plurality of power converters 10 connected in series on their input sides, and a control unit 20 that provides feedback control to the power converters 10. The control unit 20 corrects the on-time of the plurality of power converters 10 using a reference voltage based on the input voltages of the plurality of power converters 10. In particular, the control unit 20 performs the control shown in Figures 3 to 5, which will be described later.

[0019] The power converter 10 is a so-called converter, and includes DC-DC converters, DC-AC converters, AC-DC converters, AC-AC converters, or feedforward control that also detects the input voltage. In addition, it can also be applied to bidirectional power converters (for example, DAB converters (isolated bidirectional power converters)). That is, multiple power converters 10 may be connected to each other in series or parallel on the input side, and may also be connected to each other in series or parallel on the output side.

[0020] Conventionally, when controlling multiple connected power converters 10, each power converter 10 (11 to 1N) is provided with its own feedback control circuit. Each power converter 10 (11 to 1N) was individually controlled by its own feedback control circuit. In contrast, the power converter control device 1 of the present invention sets the number of control units that perform the role of a feedback control circuit to any number less than or equal to the number of power converters 10 installed.

[0021] In the embodiment shown in Figure 1, the power converter control device 1 consists of only one control unit 20(21). Figure 2 is a diagram illustrating the configuration of a power converter control device according to another embodiment of the present invention. In the embodiment shown in Figure 2, the power converter control device 1 is configured such that each power converter 10 (11 to 1N) is provided with a control unit 20 (21 to 2N), but the number of control units 20 can be arbitrary. In the power converter control device shown in Figures 1 and 2, the control unit 20 detects the input voltage of each power converter 10 (information on the input voltage of each power converter 10 is sent to the control unit 20).

[0022] [Control Unit] Figure 3 is a diagram illustrating the configuration of a control unit (control circuit) according to an embodiment of the present invention. As shown in Figure 3, the control unit 20 includes a differential amplifier 31, a compensation circuit 32, and a PWM generation circuit 33. The control unit 20 generates a reference voltage E based on the input voltage of each power converter 10. r1This controls the ON time of the power converter 10. In other words, the reference voltage E of each power converter 10 r1 By controlling based on this, the input voltages of each power converter 10 are balanced. Timing adjustment is performed by inputting a sawtooth wave timing signal to the non-inverting input terminal of the compensation circuit 32. This timing signal is generated using a generator (not shown).

[0023] Reference voltage E based on the input voltage of power converter 10(11) r1 This can be calculated using the following equation (1). Note that the following equation (2) is calculated using the reference voltage E of the Nth power converter 10. rN This is the formula for finding E, and formula (3) below is the general formula. Note that in the formula, E * r1 , E * rN , E * rn This is a fixed value that is set in advance when the power converter control device starts operating, and is a voltage value that can be varied by external adjustment.

[0024]

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[0025]

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[0026]

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[0027] Thus, the control unit 20(21) uses the reference voltage E r1 Calculate this reference voltage E r1 This controls the on-time of the power converter 10 to compensate for it. In the above equations (1), (2), and (3), Q is a coefficient based on the number of control units, and K is E in equation (1). r1 and all E iThere is a coefficient that determines how small the difference from the mean value should be, and the same applies to other formulas. When Q=1, the above formula (1) becomes as follows.

number

[0028] As shown in Figure 2, in a power converter control device equipped with multiple power converters 10 (11 to 1N), each power converter 10 (11 to 1N) is provided with a control unit 20 (21 to 2N), the reference voltage E of the nth other power converter 1n rn As shown in Figure 4, it is controlled by the voltage calculated by equation (3) above or equation (4) below. Note that if the number of control units 20 with Q=1 is 1, it is controlled by the voltage calculated by equation (1') above. In particular, using the following formula (4), E i1 and E i2 , E i2 and E i3 , , , E iN-1 and E iN By repeating the comparison every 2 to M units, the balance of each input voltage can be achieved. In equation (4) below, K' is the same coefficient as K above, and Q' is the same coefficient as Q above.

[0029]

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[0030] In other words, as shown in Figure 3, the control unit 20(21) is provided in only one power converter 10(11), and the other power converters 10(12~1N) can also be controlled as if they had the same input voltage as the said power converter 10(11). Alternatively, as shown in Figure 4, other power converters 10 (12~1N) can also be controlled by a reference voltage based on equations (3), (4), and (1').

[0031] The control unit 20 shown in Figure 4 includes a differential amplifier 31, a compensation circuit 32, and a PWM generation circuit 33. A reference voltage based on the above equations (3), (4), and (1') is input to the non-inverting input terminal of the differential amplifier 31, generating a control signal to control the power converter 10 (11~1N). In this case as well, timing adjustment is performed by inputting a sawtooth wave timing signal to the non-inverting input terminal of the compensation circuit 32. This timing signal is generated using a generator (not shown).

[0032] When the number of control units 20 is two or more and less than or equal to the number of power converters 10 (11 to 1N), each control unit 20 (21, 22, 23, 2N) corrects the on-time of multiple power converters 10 (11 to 1N) using the average value of the on-time when each power converter 10 (11, 12, 13, 1N) is corrected individually. In other words, the control unit 20 provided in each power converter 10 performs feedback control to control the reference voltage of each power converter 10.

[0033] In this case, a power converter 10 that does not have a control unit 20 will use a control signal generated by a control unit 20 installed in an adjacent power converter 10.

[0034] Alternatively, as shown in Figure 5, the input voltage E of the power converter 10 in And the input voltage E of the adjacent power converter 10 in―1 The difference between these two values ​​may be used to activate the comparator 34 and adjust the control signal.

[0035] In comparator 34, E in >E in―1 In this case, E in Reduce the ON time by a predetermined amount, and as a result E in The signal adjustment is performed to increase the off-time by a predetermined amount of time. Also, E in <E in―1 In this case, E in The ON time is increased by a predetermined amount of time, and as a result E in The signal is being adjusted to reduce the off-time by a predetermined period.

[0036] In the embodiments described above, the control unit 20 was described in a case where it is configured using electronic elements such as a differential amplifier 31, a compensation circuit 32, or a comparator 34. However, the control unit 20 may also be configured as a control signal generation means that generates control signals by executing an appropriate program.

[0037] As described above, the power converter control device 1 can control the balance of the input voltages of multiple power converters connected in series.

[0038] For example, Figure 6 shows the simulation results when the power converter control device according to an embodiment of the present invention is applied to the 2-series input-2-series output converter described above. According to the power converter control device of the present invention, as shown in Figure 6, V in1 and V in2 Both were 750V, allowing for control over the balance of the input voltage.

[0039] Furthermore, as described above, the power converter control device of the present invention can control the balance of the input voltage simply by detecting the input voltage. Therefore, it is easier to implement than balance control using the input current, which is difficult to detect.

[0040] The power converter control device 1 described above is an example of the power converter control device of the present invention, and the configuration of the present invention is not limited to that example, without departing from the spirit of the present invention.

[0041] For example, when the control unit 20 corrects the on-time of multiple power converters 10 (11 to 1N), it can employ a control method that compares the input voltage of a reference power converter (e.g., power converter 11) with the input voltage of the other power converters (e.g., power converters 12 to 1N) one by one and corrects the on-time.

[0042] Alternatively, the control unit 20 can employ a control method that corrects the on-time by repeatedly processing in parallel the input voltage of a reference power converter (e.g., power converter 11) and the input voltages of other power converters (e.g., power converters 12-1N) among the power converters 10. [Industrial applicability]

[0043] The power converter control device according to the present invention has a simple structure and can control the balance of the input voltages of multiple power converters connected in series, making it industrially useful in various situations. [Explanation of Symbols]

[0044] 1. Power converter control device 10, 11, 12, 13, 1N Power Converter 20,21,22,23,2N Control part 31 Differential Amplifier 32 Compensation circuit 33 PWM generation circuit 34 Comparator

Claims

1. Multiple power converters, A power converter control device comprising a control unit for feedback control of the power converters, and a control unit for correcting the on-time of the plurality of power converters based on a reference voltage derived from the input voltages of the plurality of power converters, When the number of control units is one, the control unit is a power converter control device that corrects the on-time of multiple power converters so that all of the multiple power converters have the same input voltage.

2. Multiple power converters, A power converter control device comprising a control unit for feedback control of the power converters, and a control unit for correcting the on-time of the plurality of power converters based on a reference voltage derived from the input voltages of the plurality of power converters, A power converter control device in which, when the number of control units is two or more and less than the number of power converters, the two or more control units correct the on-time of the multiple power converters using the average value of the on-time when each of the two or more control units corrects the power converters individually.

3. When the control unit corrects the on-time of the multiple power converters, The on-time is corrected by comparing the input voltage of a reference power converter with the input voltage of each other power converter. Alternatively, the power converter control device according to claim 1 or 2, wherein the on-time is corrected by repeatedly processing in parallel the input voltage of a reference power converter and the input voltage of other power converters at the same time.

4. The power converter control device according to claim 3, wherein the control unit determines the difference between the input voltage of a reference power converter and the input voltage of another power converter using a comparator, and corrects the on-width and off-width of the input voltage of the other power converter using a counter based on the difference.

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