JP6941510B2 - Control method of control device and power converter - Google Patents

Description

The present invention relates to a control method for a control device and a power conversion device.

Conventionally, there is a control device that controls a voltage conversion device that raises and lowers the voltage of a power source (for example, a lead battery) mounted on a vehicle and outputs the voltage to an inverter. In such a control device, the voltage conversion device is controlled by using feedforward calculation and feedback calculation.

Japanese Unexamined Patent Publication No. 2015-2018

However, in the prior art, when the energization path of the voltage converter is switched, the current output by the voltage converter oscillates, which may reduce the responsiveness of the voltage converter.

The present invention has been made in view of the above, and an object of the present invention is to provide a control device and a control method capable of improving the responsiveness of the power conversion device.

The control device according to the embodiment includes a switching unit and a correction unit. The switching unit has a first mode in which the switching element on the output side of the power conversion device is turned off and a current is output via the parasitic diode, and a first mode in which the switching element is turned on and the current is output via the switching element. Switch between 2 modes. The correction unit corrects the drive signal input to the power conversion device when the switching unit switches from one mode to the other mode.

According to the present invention, the responsiveness of the power conversion device can be improved.

FIG. 1 is a block diagram of a power supply system. FIG. 2 is a block diagram of the converter control device. FIG. 3A is a diagram showing a specific example of the circuit diagram of the converter. FIG. 3B is a diagram showing a first mode at the time of boosting. FIG. 3C is a diagram showing a second mode at the time of boosting. FIG. 4 is a timing chart showing the timing of correction by the correction unit. FIG. 5 is a diagram showing the output current after correction. FIG. 6 is a flowchart showing a processing procedure executed by the converter control device.

Hereinafter, the control method of the control device and the power conversion device according to the embodiment will be described in detail with reference to the accompanying drawings. The present invention is not limited to this embodiment.

First, the power supply system S including the control device according to the embodiment will be described with reference to FIG. FIG. 1 is a block diagram of the power supply system S according to the embodiment. The power supply system S includes a vehicle power supply device 1, a lead battery 3, an electric load 4, a lithium ion battery (LIB) 5, a generator 6, and a starter 7.

The lead battery 3 is a secondary battery using lead as an electrode. The lead battery 3 serves as a main power source for electrical equipment mounted on the vehicle. The electric load 4 is an electric device provided in the vehicle. For example, examples of the electric load 4 include a navigation device, an audio system, an air conditioner, and the like. Alternatively, for example, the electric load 4 may be a vehicle control device that controls a vehicle such as a PCS (Pre-crash Safety System) or an AEB (Advanced Emergency Braking System).

The LIB 5 is a storage battery that stores electric charges. The LIB 5 is an auxiliary power source for the lead battery 3. The auxiliary power supply may be a power storage device, and may be a capacitor or another secondary battery instead of the LIB 5.

The generator 6 is a device that generates electric power by using the rotation of an engine as a power source. In addition, when the vehicle is decelerating, regenerative electric power is generated by the regenerative brake. The generator 6 may be called an alternator or a generator.

The generator 6 generates electric power in response to an instruction from an engine control device (not shown), for example. For example, the lead battery 3 and the LIB 5 are charged by supplying the generated electric power to the lead battery 3 and the LIB 5.

The starter 7 is a starting device including an electric motor and starting an engine. Although it is assumed here that the power supply system S includes the starter 7 and the generator 6, an ISG (Integrated Starter Generator) may be provided instead of the starter 7 and the generator 6.

The vehicle power supply device 1 controls the entire power supply system S. Further, the vehicle power supply device 1 includes a first switch unit 11, a second switch unit 12, a power supply control device 13, a DCDC converter 14, and a converter control device 15.

The first and second switch units 11 and 12 are switches (relays) that control short circuits and open circuits. The first switch unit 11 is connected between the lead battery 3 and the generator 6 and between the lead battery 3 and the starter 7. The second switch unit 12 is connected between the LIB 5 and the generator 6 and between the LIB 5 and the starter 7. One ends of the first switch unit 11 and the second switch unit 12 are connected to each other, and opening / closing (on / off) is controlled by a power supply control device 13 described later. The number and arrangement of the first and second switch units 11 and 12 shown in FIG. 1 is an example, and is not limited to this. For example, even if the vehicle power supply device 1 has three or more switch units. good.

The power control device 13 includes, for example, a microcomputer having a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), an input / output port, and various circuits. Then, the power supply control device 13 executes the program stored in the ROM by the CPU using the RAM as a work area, thereby causing the switch control unit 13a, the drive signal generation unit 13b, the vehicle state acquisition unit 13c, and the like. It functions as a charge state acquisition unit 13d.

The switch control unit 13a controls the open / closed state of the first switch unit 11 and the second switch unit 12 with reference to the charging state of the lead battery 3 and the LIB 5, the current consumption of the electric load 4, the vehicle state, and the like.

The drive signal generation unit 13b controls the drive state of the DCDC converter 14 according to the charging state of the lead battery 3 and the LIB 5, the current consumption of the electric load 4, the state of the vehicle, and the like. Specifically, the drive signal generation unit 13b generates a target drive signal corresponding to the target output current of the DCDC converter 14 and outputs the target drive signal to the converter control device 15.

The vehicle state acquisition unit 13c acquires the state of the vehicle from an in-vehicle sensor (not shown). The state of the vehicle includes the running state of the vehicle and the driving state of the engine. The traveling state of the vehicle is a state in which the vehicle is traveling, decelerating, or the like. The vehicle state acquisition unit 13c determines a state in which the vehicle is running or decelerating based on a signal output from, for example, a vehicle speed sensor among the in-vehicle sensors.

The driving state of the engine is when the engine is started for the first time, when the engine is restarted from the idling stop (when returning), and the like. The first time the engine is started is when the driver gets into the vehicle and operates keys and buttons to start the engine for the first time. When restarting from idling stop (when returning) is when the engine is temporarily stopped (idling stop) while waiting for a traffic light, etc., and then restarted when the driver operates the accelerator. ..

The charge state acquisition unit 13d acquires the charge state of the lead battery 3 and the LIB 5. The DCDC converter 14 is a voltage conversion device that converts (steps down or boosts) a DC voltage (input voltage) into another DC voltage (output voltage).

The DCDC converter 14 is connected between the lead battery 3 and the LIB 5 and between the electric load 4 and the LIB 5. Further, one end of the DCDC converter 14 is connected to the first switch unit 11, and the other end is connected to the second switch unit 12.

For example, when power is supplied from the LIB 5 to the lead battery 3, the DCDC converter 14 boosts the voltage of the LIB 5 and supplies the power to the lead battery 3. Further, when the electric power is supplied from the LIB 5 to the electric load 4, the DCDC converter 14 boosts or lowers the voltage of the LIB 5 and supplies the electric power to the electric load 4.

The converter control device 15 is a control device that controls the DCDC converter 14. The converter control device 15 controls the DCDC converter 14 based on the drive signal input from the power supply control device 13. The details of the converter control device 15 will be described later with reference to FIG.

Next, the configuration of the converter control device 15 will be described with reference to FIG. FIG. 2 is a block diagram of the converter control device 15. The converter control device 15 includes a generation unit 15a, a switching unit 15b, and a correction unit 15c.

The generation unit 15a includes a proportional calculation unit 155, an integration calculation unit 154, an integrator 156, and an adder 157.

The proportional calculation unit 155 calculates a proportional operation amount proportional to the difference between the target drive signal and the output signal of the DCDC converter 14. For example, when the DCDC converter 14 is current-controlled, the proportional calculation unit 155 calculates a proportional operation amount proportional to the difference between the target drive signal, which is the target current, and the output current of the DCDC converter 14.

The integration calculation unit 154 obtains a calculation value corresponding to the difference between the target drive signal and the output current of the DCDC converter 14 and the integration gain, and outputs the calculation value to the integrator 156. The integrator 156 integrates the calculated values calculated by the integrator calculation unit 154 to calculate the integral operation amount.

The adder 157 adds the proportional operation amount calculated by the proportional calculation unit 155 and the integral operation amount calculated by the integrator 156 to generate a control signal, and outputs the control signal to the DCDC converter 14. As a result, the DCDC converter 14 outputs an output voltage corresponding to the control signal.

The switching unit 15b switches the output mode of the DCDC converter 14 according to the output current of the DCDC converter 14. Further, the switching unit 15b turns on the switch SW1 when switching the output mode. As a result, the correction signal generated by the correction unit 15c, which will be described later, is input to the generation unit 15a. Here, the configuration of the DCDC converter 14 and the details of the output mode will be described with reference to FIGS. 3A to 3C.

FIG. 3A is a diagram showing a configuration example of the DCDC converter 14. As shown in FIG. 3A, the DCDC converter 14 is a so-called H-bridge type converter and includes switching elements Q1 to Q4, parasitic diodes D1 to D4, and an inductor L.

Although FIG. 3A shows a case where each switching element Q1 to Q4 is a MOSFET (Metal Oxide Semiconductor Field Effect Transistor), it may be another charge effect transistor such as an IGBT (Insulated Gate Bipolar Transistor). good. Further, parasitic diodes D1 to D4 are connected between the source and drain of the switching elements Q1 to Q4, respectively.

The control signal generated by the generation unit 15a described above corresponds to the pulse width (duty ratio) of the gate voltage that controls the on / off of the switching elements Q1 to Q4. Further, the DCDC converter 14 can step up or down in both directions, but in the following, the input voltage input from the left side (switching element Q1 side) in the figure is boosted to raise the output voltage to the right side (switching element Q1 side) in the figure. A case of outputting from the switching element Q3 side) will be described.

FIG. 3B is a diagram showing a first mode at the time of boosting. As shown in FIG. 3B, the converter control device 15 turns on / off the switching element Q4 in the first mode with the switching element Q1 of the DCDC converter 14 turned on and the switching element Q2 and the switching element Q3 turned off. Switch.

As a result, energy can be stored in the inductor L by electromagnetic induction, and the input voltage can be boosted to a desired output voltage. Further, the output voltage boosted in the first mode is output via the parasitic diode D3. As described above, the first mode is a mode in which the current is output from the DCDC converter 14 via the parasitic diode D3 on the output side.

In the first mode, since the switching element Q3 is turned off, it is possible to prevent the backflow of current from the switching element Q3 side to the switching element Q1 side. That is, when the boosted voltage is lower than the voltage on the output side (switching element Q3 side), the backflow of current from the output side to the input side can be suppressed.

However, if the switching element Q3 is left off, a large current flows through the parasitic diode D3 when the output current becomes large. As a result, the parasitic diode D3 generates heat and may be burnt out.

Therefore, the switching unit 15b switches the output mode of the DCDC converter 14 from the first mode to the second mode when the output current of the DCDC converter 14 exceeds the switching point Tp.

Here, the switching point Tp corresponds to, for example, the allowable current of the parasitic diode D3. As a result, since a current exceeding the switching point Tp does not flow through the parasitic diode D3, it is possible to prevent the parasitic diode D3 from burning due to heat generation and to extend the life of the parasitic diode D3.

FIG. 3C is a diagram showing a second mode at the time of boosting. As shown in FIG. 3C, the second mode is a mode in which the switching element Q3 and the switching element Q4 are alternately turned on / off while the switching element Q1 on the input side is on and the switching element Q2 is off. .. Specifically, the second mode is a mode in which the switching element Q4 is off when the switching element Q3 is on, and the switching element Q4 is on when the switching element Q3 is off.

That is, in the first mode, the current was output through the current path via the parasitic diode D3 (hereinafter, also referred to as the first path), whereas in the second mode, the current path via the switching element Q3. The current is output by (hereinafter, also referred to as the second path). As described above, in the second mode, the heat generation of the parasitic diode D3 can be suppressed, and the burning of the parasitic diode D3 can be suppressed.

By the way, in the first path, since the current flows through the parasitic diode D3, the energization loss becomes larger than that in the second path by the amount of the resistance of the parasitic diode D3. That is, the first mode and the second mode have different energization losses.

Therefore, when the output mode is switched between the first mode and the second mode, the output current of the DCDC converter 14 fluctuates at the timing when the energization path is switched. Specifically, it is assumed that the voltage is boosted to 13V in the first mode and the voltage is stepped down to 12V due to the energization loss due to the parasitic diode D3.

In such a case, when the mode is switched from the first mode to the second mode, the voltage of 13 V is output as it is (here, it is assumed that the energization loss (resistance) by the switching element Q3 is zero).

Due to such voltage fluctuations, the output current of the DCDC converter 14 oscillates, and the responsiveness of the DCDC converter 14 deteriorates. Further, the fluctuation of the voltage may cause an overshoot or undershoot of the output current.

Therefore, in the converter control device 15 according to the embodiment, the control signal is corrected at the timing when the output mode is switched. This makes it possible to suppress the oscillation of the output current of the DCDC converter 14 and improve the responsiveness of the DCDC converter 14.

Specifically, the converter control device 15 includes a correction unit 15c that corrects the control signal. Here, returning to the description of FIG. 2, the correction unit 15c will be described. As shown in FIG. 2, the correction unit 15c includes a correction signal generation unit 153 and a switch SW1. The correction signal generation unit 153 corrects the control signal by generating a correction signal according to the drive signal and outputting the correction signal to the generation unit 15a via the switch SW1.

Such a correction signal is added or subtracted from the calculated value output by the integrator calculation unit 154, and is input to the integrator 156. Specifically, when switching from the first mode to the second mode, the correction signal is subtracted from the calculated value, and when switching from the second mode to the first mode, the correction signal is added to the calculated value.

That is, when switching from the first mode to the second mode, the energization loss of the energization path becomes smaller as described above, so the difference in the energization loss between the first path and the second path is subtracted from the calculated value. On the other hand, when switching from the second mode to the first mode, the energization loss becomes large, so the difference in the energization loss between the first path and the second path is added to the calculated value.

That is, the correction unit 15c eliminates or compensates for the difference in energization loss when the output mode is switched. As a result, fluctuations in the output current when switching the output mode can be suppressed.

Therefore, when the output mode is switched, the oscillation of the output current of the DCDC converter 14 can be suppressed, so that the responsiveness of the DCDC converter 14 can be improved.

Further, after the correction signal is added or subtracted from the calculated value, the corrected calculated value is integrated by the integrator 156. As a result, the effect of the subsequent correction can be maintained by inputting the correction signal once. That is, the correction unit 15c can input the correction signal to the integration calculation unit 154 to minimize the number of corrections of the calculated value.

The switch SW1 is controlled on / off by, for example, the switching unit 15b. Further, one end of the switch SW1 is connected to the correction signal generation unit 153, and the other end is connected to the generation unit 15a.

For example, when the switching unit 15b switches the output mode, the switch SW1 is turned on by the control of the switching unit 15b, and then turned off after a certain period of time. That is, the switch SW1 is turned on only for a certain period of time when the output mode is switched from the first mode to the second mode and from the second mode to the first mode.

Such a fixed period is one cycle of feedback control performed by the generation unit 15a. As a result, as described above, the correction signal is input to the integrator 156 only at the timing when the output mode is switched.

Next, the correction timing of the correction unit 15c will be described with reference to FIG. FIG. 4 is a timing chart showing the timing of correction by the correction unit 15c.

As shown in A of FIG. 4, the switching unit 15b switches the output mode from the first mode to the second mode as shown in B of FIG. 4 at the time t1 when the output current of the DCDC converter 14 exceeds the switching point Tp.

At this time, as shown in C of FIG. 4, the switching unit 15b turns on the switch SW1 only for a predetermined period from the time t1 to the time t2. As a result, as shown in D in the figure, the correction signal generated by the correction signal generation unit 153 is subtracted from the control signal.

After that, as shown in A of the figure, at time t3 when the output current falls below the switching point Tp, the switching unit 15b switches the output mode from the second mode to the first mode as shown in B of the figure.

At this time, as shown in C of the figure, the switch SW1 is turned on for a predetermined period from the time t3 to the time t4. As a result, the correction signal is added to the control signal.

In this way, the converter control device 15 adds or subtracts the correction signal when the output mode is switched. As a result, as shown in E of FIG. 4, the control signal of the first mode input to the DCDC converter 14 can be made larger than the control signal of the second mode.

That is, it is possible to fill the difference in the energization loss between the first path and the second path that occurs when the output mode is switched. As a result, it is possible to suppress oscillation based on fluctuations in the output current when the output mode is switched.

FIG. 5 is a diagram showing the output current after correction. As described above, the switching unit 15b switches the output mode of the DCDC converter 14 when the output current of the DCDC converter 14 exceeds the switching point Tp or when the output current falls below the switching point Tp.

Then, the correction unit 15c corrects the control signal according to the timing at which the output mode is switched. As a result, the converter control device 15 can improve the responsiveness of the DCDC converter 14 to the drive signal input from the power supply control device 13 shown in FIG.

Next, a processing procedure executed by the converter control device 15 according to the embodiment will be described with reference to FIG. FIG. 6 is a flowchart showing a processing procedure executed by the converter control device 15. The processing procedure is repeatedly executed by the converter control device 15.

As shown in FIG. 6, the converter control device 15 determines whether or not the output mode of the DCDC converter 14 is the first mode (step S101). Here, if the output mode is the first mode (step S101, Yes), it is determined whether or not the output current of the DCDC converter 14 is smaller than the switching point Tp (step S102).

When the output current is smaller than the switching point Tp (steps S102, Yes), the determination process of step S102 is continuously performed. On the other hand, when the output current is equal to or higher than the switching point Tp (step S102, No), the output mode is switched from the first mode to the second mode (step S103). Subsequently, the correction unit 15c subtracts the correction signal from the calculated value (step S104), and the generation unit 15a outputs the corrected control signal (step S105) to end the process.

On the other hand, when the output mode is not the first mode (step S101, No), the switching unit 15b determines whether or not the output current is larger than the switching point Tp (step S106).

Here, when the output current is larger than the switching point Tp (steps S106, Yes), the determination process of step S106 is continuously performed. When the output current is equal to or less than the switching point Tp (step S106, No), the output mode of the DCDC converter 14 is switched to the first mode (step S107).

Then, the correction unit 15c adds the correction signal to the calculated value (step S108), and the generation unit 15a outputs the corrected control signal (step S105) to end the process.

As described above, the control device (converter control device 15) according to the embodiment includes a switching unit 15b and a correction unit 15c. The switching unit 15b sets the switching element Q in the first mode in which the switching element Q on the output side of the power converter (DCDC converter 14) is turned off and the current is output via the parasitic diode D, and the switching element Q is turned on. It switches between the second mode and the second mode in which the current is output via.

The correction unit 15c corrects the control signal input to the power conversion device when the switching unit 15b switches from one mode to the other mode. Therefore, according to the control device according to the embodiment, the responsiveness of the power conversion device can be improved.

By the way, in the above-described embodiment, the case where the converter control device 15 controls the DCDC converter 14 used in the power supply system S for the vehicle has been described, but the present invention is not limited to this. That is, the converter control device 15 can be applied as a control device for various DCDC converters.

Further effects and variations can be easily derived by those skilled in the art. For this reason, the broader aspects of the invention are not limited to the particular details and representative embodiments expressed and described above. Therefore, various modifications can be made without departing from the spirit or scope of the general concept of the invention as defined by the appended claims and their equivalents.

14 DCDC converter 15 Converter controller 15a Generator 15b Switching unit 15c Correction unit Q Switching element D Parasitic diode Tp switching point

Claims (4)

The first mode in which the switching element on the output side of the power converter is turned off and the current is output via the parasitic diode is switched between the first mode in which the switching element is turned on and the current is output via the switching element. Switching part and
A correction unit that corrects a control signal that controls the power conversion device when the switching unit switches from one mode to the other mode .
It includes a generator that generates the control signal based on proportional control and integral control .
The correction unit
A control device characterized in that a correction signal is input to the integral control and the control signal is corrected. The correction unit
The control device according to claim 1 , wherein the correction signal is input according to the difference in energization loss between the first mode and the second mode. The correction unit
Claim 1 or 2 is characterized in that when switching from the first mode to the second mode, the correction signal is subtracted, and when switching from the second mode to the first mode, the correction signal is added. The control device described in. The first mode in which the switching element on the output side of the power converter is turned off and the current is output via the parasitic diode is switched between the first mode in which the switching element is turned on and the current is output via the switching element. Switching process and
A correction step of correcting a control signal input to the power conversion device when switching from one mode to the other mode by the switching step, and a correction step of correcting the control signal input to the power conversion device .
Look including a generating step of generating the control signal based on proportional control and integral control,
The correction step is
A control method of a power conversion device, characterized in that a correction signal is input to the integration control and the control signal is corrected.

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