JP5128195B2 - Drive controller for buck-boost converter - Google Patents

Description

  The present invention includes a step-up / down converter drive control device that includes a step-up switching element and a step-down switching element and performs control of power supply to a load and control of supply of regenerative power obtained from the load to a storage element. About.

Conventionally, in a general buck-boost converter, the duty command for driving the step-up switching element and the step-down switching element is a feedback system PI (using the value of the current flowing through the reactor or the value of the output voltage). It is derived by Proportional Integral) control (for example, see Patent Document 1).
JP 2005-176567 A

  By the way, in such a step-up / step-down converter, since the rise of current by feedback control is delayed, there is a problem that the response of the current is delayed with respect to the duty command when switching the step-up / step-down.

  In particular, when the above-mentioned buck-boost converter is applied to a hybrid heavy machine that is a part of a drive system of a so-called heavy machine such as a construction machine, it handles less power than a hybrid car or the like. Therefore, there is a risk that deterioration of controllability due to a response delay when switching between the power running operation and the regenerative operation of the electric motor (that is, when switching the step-up / step-down pressure) may become apparent.

  In addition, there is a method for improving the responsiveness by increasing the gain of PI control with respect to the delay in the current response in such feedback control. However, when the input fluctuates rapidly, the overshoot becomes large and the PI control is increased. There is a problem in that the amount of computation increases and controllability deteriorates.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a drive control device for a step-up / step-down converter with improved responsiveness at the time of switching a step-up / step-down operation.

  A drive control device for a buck-boost converter according to one aspect of the present invention stores a first terminal for transferring power to and from an electric motor that performs both power running operation and regenerative operation, and electric power supplied to the electric motor. A second terminal to which a power supply is connected; a step-up switching element for controlling the supply of power to the motor; and a step-down switching element for controlling the supply of regenerative power obtained from the motor to the power supply And a step-up / step-down converter drive control device including a step-up switching element, a step-down switching element and a reactor connected between the second terminal and the first voltage value of the first terminal First voltage detecting means for detecting, second voltage detecting means for detecting a second voltage value of the second terminal, first voltage value detected by the first voltage detecting means, and the second voltage Control means for correcting the duty ratio for driving the step-up switching element and the step-down switching element at the time of switching of the step-up / step-down operation by feedforward control using the second voltage value detected by the output means; Is provided.

  The control means may include a PI controller, and correct the duty ratio by adding the duty ratio output by the PI controller and the duty ratio by the feedforward control.

  Alternatively, the control unit corrects the duty ratio based on a ratio between the first voltage value and the second voltage value when switching to a boost operation or switching to a step-down operation. Then, the boosting switching element may be driven.

  Further, the control means may drive the boosting switching element by correcting the duty ratio with an initial value D0 represented by D0 = 1− (E / V) when switching to the boosting operation.

  The control means may drive the step-down switching element by correcting the duty ratio with an initial value D0 represented by D0 = E / V when switching to the step-down operation.

  According to the present invention, it is possible to provide a specific effect that it is possible to provide a drive control device for a step-up / step-down converter with improved responsiveness at the time of switching a step-up / step-down operation.

  Hereinafter, an embodiment to which a drive control device for a buck-boost converter according to the present invention is applied will be described.

  FIG. 1 is a diagram schematically showing a circuit configuration of the buck-boost converter according to the present embodiment. This step-up / down converter includes a reactor 1, a step-up IGBT (Insulated Gate Bipolar Transistor) 2, a step-down IGBT 3, a power supply connection terminal 5 for connecting a capacitor 4 used as a power supply, and an output terminal 7 for connecting a motor 6. , A smoothing capacitor 8 inserted in parallel with the pair of output terminals 7, and a reactor current detection unit 9.

  In FIG. 1, a capacitor 4 is shown as a power storage element used as a power source. This power storage element may be a secondary battery that can be charged and discharged, or a power source of another form that can transmit and receive power. Good. Further, the motor 6 connected to the output terminal 7 may be an electric motor capable of power running operation and regenerative operation.

  Reactor 1 has one end connected between boosting IGBT 2 and step-down IGBT 3 and the other end connected to power supply connection terminal 5. The smoothing capacitor 8 is inserted between the positive terminal and the negative terminal of the output terminal 7 to smooth the output voltage.

  Reactor current detection unit 9 includes a resistor that detects the value of current flowing through reactor 1. The detected current value is used for feedforward control described later.

  The power supply connection terminal 5 and the output terminal 7 are provided with detection units for detecting the power supply voltage and the output voltage, respectively. The two detected voltage values are used for feedforward control described later.

  In such a step-up / step-down converter, when a boosting operation is performed, the drive control unit applies a pulse voltage to the gate terminal of the boosting IGBT 2 and performs PWM driving, thereby boosting the voltage value of the capacitor 4 and reducing the voltage. Electric power is supplied to the motor 6 through a diode connected in parallel to the IGBT 3 for use.

  Further, when performing the step-down operation, the drive controller applies a pulse voltage to the gate terminal of the step-down IGBT 3 and performs PWM driving, thereby charging the capacitor 4 with regenerative energy obtained from the motor 6.

  The step-up / step-down operation is realized as described above.

  The buck-boost converter according to the present embodiment can be applied to, for example, a power supply control unit of a hybrid construction machine. As a specific example, a configuration in which the angle operation of the arm of the construction machine is driven and controlled by an electric motor, a mode in which a bucket link is electrically driven or a lifting magnet is electrified, or a driving device for an endless track for traveling Can be used for a power supply control unit in a form of electrification or hybridization.

  In these applications, for example, the voltage value of the capacitor 4 is about 100 to 300 V, the rated output voltage at the output terminal 7 is about 360 V, the rated output is about 20 kW, the instantaneous maximum output power is ± 60 kW, the rated current is ± 55 A, the instantaneous The maximum current is about ± 170A.

  Therefore, the reactor 1, the step-up IGBT 2, the step-down IGBT 3, the power connection terminal 5, the output terminal 7, the capacitor 8, and the reactor current detection unit 9 in the present embodiment are as one step-up / down converter shown in FIG. It is required to be able to withstand such applications.

  The step-up IGBT 2 and the step-down IGBT 3 are PWM-driven by a PWM (Pulse Width Modulation) control unit described later. That is, a driving pulse voltage is applied to the gate terminals of the IGBTs 2 and 3 from the drive control unit. Such a control unit can be realized by either an electronic circuit or an arithmetic processing unit.

  FIG. 2 is a diagram showing a circuit configuration of the buck-boost converter according to the present embodiment in a control block. As shown in this figure, the control unit 10 of the buck-boost converter according to the present embodiment includes a voltage PI control unit 11, a current PI control unit 12, a PWM control unit 13, a drive state switching unit 14, and a duty correction unit 15. And a switching unit 16.

  The voltage PI control unit 11 calculates a target current value ict * by PI control based on the voltage target value V * and the output voltage value of the output terminal 7.

  The current PI control unit 12 includes an absolute value output unit 12a, and performs PI control based on the target current value ict * and the current value ic flowing through the reactor via the absolute value output unit 12a. D is calculated. Therefore, the target duty command value D takes a positive value.

  The PWM control unit 13 calculates a duty command value based on the target duty command value D and the duty correction value D0, and performs drive control of the step-up switching element 2 and the step-down switching element 3. Note that the duty command value is distinguished from the value at the time of step-up operation by adding a negative sign to the value at the time of step-down operation.

  The drive state switching unit 14 switches the drive state of the step-up / step-down converter to one of “step-up PWM control”, “OFF (OFF)”, and “step-down PWM control”. This switching is performed based on the voltage target value V * and the inter-terminal voltage value V of the output terminal 7. When “voltage target value V * −inter-terminal voltage value V> 0”, “step-up PWM control” is set. When “voltage target value V * −terminal voltage value V≈0”, it is switched to “OFF”, and when “voltage target value V * −terminal voltage value V <0”, “ It is switched to “step-down PWM control”.

  In the step-up / step-down converter, the voltage value E of the capacitor 4 as a power source (that is, the voltage value between the terminals of the power supply connection terminal 5, hereinafter referred to as “power supply voltage E”), the current flowing through the reactor 1 (hereinafter referred to as “reactor current”). ) (Hereinafter referred to as “reactor current value ict”) and the voltage V between terminals of the output terminal 7 (hereinafter referred to as “output voltage V”) are detected. Reactor current value ict is positive in the direction flowing from power supply connection terminal 5 to output terminal 7 during the step-up operation, and negative in the direction flowing from output terminal 7 to power supply connection terminal 5 during the step-down operation.

  The duty correction unit 15 corrects the duty command value for driving the step-up switching element 2 and the step-down switching element 3 in both the step-up operation and the step-down operation.

  The switching unit 16 switches the connection between the duty correction unit 15 and the PWM control unit 13 in accordance with the step-up operation and the step-down operation.

  FIG. 3 is a characteristic diagram showing the relationship between the reactor current and the duty command in the buck-boost converter according to the present embodiment.

  As described above, in the feedback control type buck-boost converter, the response of the reactor current is delayed with respect to the duty command value in the region before and after switching of the buck-boost operation. This state is indicated by a broken line in FIG. In the buck-boost converter of the present embodiment, the response delay of the reactor current is improved by the following control process.

  When switching from the step-down operation to the step-up operation, the duty correction unit 15 uses the power supply voltage E and the output voltage V detected by the buck-boost converter at that time, and the duty expressed by D0 = 1− (E / V) The correction value D0 is calculated and sent to the PWM control unit 13.

  The PWM control unit 13 receives (D + D0) in which the target duty command value D calculated by the current PI control unit 12 is corrected by the initial value D0 of the duty ratio. The IGBT 2 is driven. Here, at the time of switching to the boost operation, the target duty command value D is substantially zero. Therefore, at the time of switching to the boosting operation, the boosting IGBT 2 is driven using the initial value D0 of the duty ratio as a correction value. As a result, as shown in the first quadrant of FIG. 3, the reactor current has no delay with respect to the duty.

  On the other hand, when switching from the step-up operation to the step-down operation, the duty correction value D0 represented by D0 = E / V is calculated using the power supply voltage E and the output voltage V detected by the step-up / step-down converter at this time. Is sent to the PWM controller 13.

  The PWM control unit 13 receives (D + D0) in which the target duty command value D calculated by the current PI control unit 12 is corrected by the initial value D0 of the duty ratio. The IGBT 3 is driven. Here, at the time of switching to the step-down operation, the target duty command value D is substantially zero. Therefore, when switching to the step-down operation, the step-down IGBT 3 is driven using the initial value D0 of the duty ratio as the correction value. As a result, as shown in the third quadrant of FIG. 3, the reactor current has no delay with respect to the duty.

  As described above, in the buck-boost converter according to the present embodiment, in order to correct the duty command value in the feed-forward type control, as shown by the solid line in FIG. Good responsiveness can be obtained.

  In particular, when applied to a power supply device such as a hybrid construction machine, since the electric power handled is much larger than that of an electric vehicle or a hybrid car, it is possible to perform a favorable switching operation of the buck-boost by improving the current response. In addition, since the occurrence of overshoot can be suppressed, the burden on the PI control system can be reduced.

  In the above description, the DC drive motor 6 is directly connected to the output terminal 7, but instead, an AC drive motor may be connected to the output terminal 7 via an inverter.

  In the above description, the mode of correcting the target duty command value D output from the current PI control unit 12 (via the absolute value output unit 12a) has been described. However, the control method is not limited to the PI control method. The target duty command value D by hysteresis control, robust control, adaptive control, proportional control, integral control, gain scheduling control, or sliding mode control may be corrected, or the target duty command by a primary or higher filter The value D may be corrected.

  As mentioned above, although the drive control apparatus of the step-up / step-down converter according to the exemplary embodiment of the present invention has been described, the present invention is not limited to the specifically disclosed embodiment, and from the claims. Various modifications and changes can be made without departing.

It is a figure which shows roughly the circuit structure of the buck-boost converter of this Embodiment. It is a figure which shows the circuit structure of the buck-boost converter of this Embodiment with a control block. It is a characteristic view which shows the relationship between the reactor electric current and duty command in the buck-boost converter of this Embodiment.

Explanation of symbols

1 Reactor 2 Boost IGBT
3 Step-down IGBT
DESCRIPTION OF SYMBOLS 4 Capacitor 5 Power supply connection terminal 6 Motor 7 Output terminal 8 Capacitor 9 Reactor current detection part 10 Buck-boost converter control part 11 Voltage PI control part 12 Current PI control part 12a Absolute value output part 13 PWM control part 14 Drive state switching Part 15 Duty correction part 16 Switching part

Claims (5)

A first terminal for transferring power to and from a motor that performs both power running and regenerative operation; a second terminal to which a power source that stores power supplied to the motor is connected; and power to the motor A step-up switching element for controlling the supply of power, a step-down switching element for controlling the supply of regenerative power obtained from the electric motor to the power source, the step-up switching element, the step-down switching element, and the A step-up / down converter drive control device including a reactor connected between the second terminal,
First voltage detecting means for detecting a first voltage value of the first terminal;
Second voltage detecting means for detecting a second voltage value of the second terminal;
Deriving a target duty command value through feedback control using the first voltage value, and the initial value of the duty ratio of the voltage step-up operation by the feed-forward control using said second voltage value and the first voltage value and It calculates the initial value of the duty ratio of the voltage step-down operation, corrects the duty ratio for driving the front Symbol boosting switching element and the voltage-falling switching element, and a control unit,
The control means adds an initial value of a duty ratio at the time of the boost operation to the target duty command value at the time of switching from the step-down operation to the step-up operation, and the target duty at the time of switching from the step-up operation to the step-down operation. Correcting the duty ratio by adding an initial value of the duty ratio during the step-down operation to the command value;
Drive controller for buck-boost converter. The control means has a PI controller, and the target duty command value output from the PI controller and the initial value of the duty ratio during the step-up operation by the feedforward control or the initial duty ratio during the step-down operation The drive control device for a step-up / down converter according to claim 1, wherein the duty ratio is corrected by adding a value . The control means is configured to calculate an initial duty ratio during the boost operation calculated based on a ratio between the first voltage value and the second voltage value when switching to the boost operation or switching to the step-down operation. The step- up / down converter drive control device according to claim 1, wherein the step-up / step-down converter is driven by correcting the duty ratio according to a value or an initial value of a duty ratio during the step-down operation . When switching to the boost operation, the control means is configured such that when the first voltage value is V and the second voltage value is E, the duty in the boost operation represented by D0 = 1− (E / V) 4. The drive control device for a step-up / down converter according to claim 3, wherein the step-up / down converter is driven by correcting the duty ratio with an initial value D0 of the ratio. When the control means switches to the step-down operation, the initial value of the duty ratio during the step-down operation represented by D0 = E / V when the first voltage value is V and the second voltage value is E 4. The drive control device for a buck-boost converter according to claim 3, wherein the step-down switching element is driven by correcting the duty ratio at D0.

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