JP2010124574A - Chopper control method of dc power supply and moving vehicle using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To control battery current so that it does not suddenly change in a chopper control circuit of a DC power supply. <P>SOLUTION: In the DC power supply, a regenerative current accumulation part R<SB>A</SB>having a capacitor C and a chopper circuit ch for boosting voltage is connected to a battery B in parallel. In a first subtraction part 36, a difference operation of an assist current command value I<SB>L</SB><SP>*</SP>flowing in the chopper circuit ch and an assist current value I<SB>L</SB>flowing in the chopper circuit ch is performed and a first difference signal is calculated. In a PWM control part 38, a gate signal corresponding to the first difference signal is generated and the chopper circuit ch is controlled, in the chopper control method. When capacitor voltage V<SB>B</SB>is lower than capacitor rated voltage V<SB>EDLC_max</SB>, the assist current command value I<SB>L</SB><SP>*</SP>or the first difference signal is restricted, and the gate signal of the chopper circuit ch is adjusted. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a DC power supply chopper control method, and more particularly to a mobile vehicle using the DC power supply chopper method.

  A mobile vehicle such as a battery forklift that uses a battery as a power source is equipped with a secondary battery such as a lead battery, for example, and charges the battery with a regenerative current generated by a motor during braking or the like. However, in the existing battery, when a regenerative current that increases rapidly during regeneration is charged, the charging efficiency is poor, and battery deterioration is accelerated and the battery life is shortened.

  For this reason, a method is employed in which a capacitor (for example, an electric double layer capacitor) is connected to the battery to suppress a sudden change in current regenerated in the battery. As one of them, there is known a method in which a battery and a capacitor are directly connected in parallel so that the regenerative power is charged in the capacitor to extend the life of the battery and the regenerative power is effectively used. However, the above method has a problem that current does not easily flow through the capacitor when the internal resistance of the capacitor is higher than the internal resistance of the battery. As a solution, there is a method of increasing the number of capacitors in parallel and reducing the internal resistance. However, this method has increased the cost.

In general, as a method for extending the battery life, a diode for a regenerative current element is connected between a DC circuit of a battery and a power converter (inverter or chopper), and regenerative energy is stored in a capacitor (Patent Document 3). Examples include a method of connecting a chopper circuit to the circuit and controlling the battery current by the chopper circuit to store regenerative energy in the capacitor.
JP-A-6-270695 JP 2002-315109 A JP 2003-219666 A

  The inventor of the present application paid attention to the following first and second problems in the method of controlling the battery current by the chopper circuit as described above.

That is, as a first problem, there is a case where the capacitor voltage V _EDLC fluctuates due to charging and discharging of the capacitor, and the capacitor voltage V _EDLC exceeds the usage range of the capacitor (capacitor voltage V _EDLC ≦ capacitor rated voltage) depending on the charge and discharge ratio. there were. Because the time has been controlled to stop charging and discharging of the capacitor, for the stopping charging and discharging of the capacitor assist current (current flowing through the chopper circuit) I _L becomes suddenly 0, the battery current changes suddenly There was a problem.

As a second problem, when charging / discharging in a state where the capacitor voltage V _EDLC is lowered, the current value at the time of charging / discharging is larger than in a state where the capacitor voltage V _EDLC is high, and loss due to the internal resistance of the capacitor is increased. It was.

  The present invention is a technical idea created to solve the above-mentioned problems, and the invention according to claims 1 to 8 is provided by adjusting the gate signal of the chopper before the capacitor voltage exceeds the capacitor rated voltage. The first problem is solved. The inventions of claims 3, 6 and 7 solve the second problem by charging and discharging the capacitor in a state where the capacitor voltage is high.

  More specifically, according to the first aspect of the present invention, in a DC power source in which a regenerative current accumulating unit having a capacitor and a chopper circuit for stepping up and down a voltage thereof is connected in parallel to the battery, the first subtracting unit includes the chopper circuit. The first difference signal is calculated by executing a difference calculation between the assist current command value to flow and the assist current value flowing to the chopper circuit, and a gate signal corresponding to the first difference signal is generated in the PWM control unit. A chopper control method for controlling the assist current, wherein when the capacitor voltage is equal to or lower than the capacitor rated voltage, the assist current command value or the first difference signal is limited, and a gate signal of the chopper circuit based on the limitation is output. It is characterized by.

  According to a second aspect of the present invention, in the first aspect of the present invention, the restriction applied to the assist current command value is to multiply the assist current command value by a gain. It is calculated by the following formulas (1) and (2) from the capacitor open voltage obtained by subtracting the value obtained by multiplying the capacitor current value and the capacitor internal resistance value from the voltage, the capacitor rated voltage, and the battery voltage. To do.

  According to a third aspect of the present invention, in the first aspect of the present invention, the restriction applied to the assist current command value is to multiply the assist current command value by a gain. The capacitor open voltage obtained by subtracting the product of the capacitor current value and the internal resistance value of the capacitor from the voltage, the lower limit voltage value and the upper limit voltage value of the discharge limit set to narrow the fluctuation range of the capacitor voltage, and charging It is calculated from the lower limit voltage value and the upper limit voltage value of the restriction by the following equations (3) and (4).

  According to a fourth aspect of the present invention, in the first aspect of the present invention, the restriction applied to the assist current command value is to multiply the assist current command value by a gain. It is calculated by the above equations (1) and (2) from the capacitor open voltage obtained by subtracting the value obtained by multiplying the assist current value and the internal resistance value of the capacitor from the voltage, the capacitor rated voltage, and the battery voltage. And

  According to a fifth aspect of the present invention, in the first aspect of the present invention, the restriction applied to the assist current command value is to multiply the assist current command value by a gain. A capacitor open voltage obtained by subtracting a value obtained by multiplying the assist current value and the internal resistance value of the capacitor from the voltage, and a lower limit voltage value and an upper limit voltage value of the capacitor discharge limit set in order to narrow the fluctuation range of the capacitor voltage, It is calculated from the lower limit voltage value and the upper limit voltage value of the capacitor charging limit by the above equations (3) and (4).

  According to a sixth aspect of the present invention, in the first aspect of the invention, the second subtraction unit calculates a second difference signal by performing a difference operation between the capacitor voltage target value and the capacitor voltage value, and the addition unit The second difference signal is added to the assist current command value.

  In the seventh aspect of the invention, the second subtraction unit performs a difference operation between the target value of the capacitor voltage and the capacitor voltage value to calculate a second difference signal, and the addition unit calculates the second difference signal as the second difference signal. The difference signal is added.

  The invention according to claim 8 is a mobile vehicle using the DC power supply chopper control method according to claims 1 to 7, wherein the DC power supply is connected to a motor of the mobile vehicle via an inverter capable of regenerative operation. It is characterized by that.

  As is apparent from the above description, according to the first to eighth aspects of the present invention, it is possible to suppress a sudden change in the battery current when charging and discharging of the capacitor is stopped, thereby reducing the burden on the battery and extending the life. It becomes possible.

  According to the third, sixth, and seventh aspects of the invention, it is possible to suppress loss due to the internal resistance of the capacitor.

  According to the fourth and fifth aspects of the invention, the current sensor for detecting the capacitor current can be omitted, and the cost can be reduced.

[Embodiment 1]
FIG. 1 is a circuit configuration diagram showing a DC power supply of a moving vehicle in the first embodiment. In FIG. 1, symbol B indicates a secondary battery such as a lead battery. An inverter INV capable of regenerative operation is connected to the battery B, and the motor M is controlled via the inverter INV. R _A indicates a regenerative current accumulating unit, which includes a chopper circuit ch having a reactor L and switching elements (eg, MOSFETs) S ₁ and S ₂ , and a capacitor C, and is connected in parallel to the battery B. Is done.

Current control using an arbitrary assist current command value I _L ^* is applied to control the switching elements S ₁ and S ₂ of the chopper circuit ch.

The arbitrary assist current command value I _L ^* is calculated, for example, as shown in the chopper control block diagram of FIG. That is, the battery voltage V _B detected by a voltage detector (not shown) is differentiated by the differentiating means 1 after noise is removed by the low-pass filter LPF1. Reference numeral 2 denotes a current command calculation unit, which performs multiplication of the signal output from the differentiating means 1 and the capacitance C _S in order to realize an ideal large-capacity capacitor current inflow to the capacitor C, thereby obtaining an assist current command value I _L ^* is calculated. The capacity C _S is a capacitor capacity for realizing the inflow of a large capacity capacitor current ideal for the capacitor, and is arbitrarily set.

  The gate signal creation unit 3 includes a determination unit 31, gain multiplication units 32a and 32b, a switching unit 33, a NOT circuit 34, a first AND circuit 35a and a second AND circuit 35b, and a first subtraction unit 36. , A PI calculation unit 37, and a PWM control unit 38.

The assist current command value I _L ^* for the chopper ch calculated by the current command calculation unit 2 is output to the determination unit 31, and the assist current command value I _L ^* is compared with 0 (that is, the assist current command value I _L ^* Positive / negative judgment). As a result of the comparison, when it is determined that the assist current command value I _L ^* ≦ 0, a signal of “0” level is output from the determination unit 31 and “1” is output to the first AND circuit 35 a via the NOT circuit 34. A level signal is output. When it is determined that the assist current command value I _L ^* ≦ 0, the switching unit 33 is switched to the gain multiplication unit 32a, and the gain multiplication unit 32a changes the assist current command value I _L ^* to the discharge gain K. _S1 is multiplied, and a switching signal is output to the first AND circuit 35a via the first subtraction unit 36, the PI calculation unit 37, and the PWM control unit 38. As a result, switching control of the switching element S ₁ is performed. In this case, although the 2AND circuit 35b a switching signal from the PWM control unit 38 is input, since the "0" level signal is inputted from the judging unit 31, the switching element S ₂ is turned off.

If the assist current command value I _L ^* > 0 is determined as a result of the comparison, a “1” level signal is output from the determination unit 31 and a “1” level signal is output to the second AND circuit 35b. Is output. When it is determined that the assist current command value I _L ^* > 0, the switching unit 33 is switched to the gain multiplication unit 32b, and the gain multiplication unit 32b sets the assist current command value I _L ^* to the charging gain K. _S2 is multiplied, and a switching signal is output to the second AND circuit 35b via the first subtractor 36, the PI calculator 37, and the PWM controller 38. As a result, the switching element S ₂ is switching control. In this case, the 1AND circuit 35a, while the switching signal from the PWM control unit 38 is output, since the "0" level signal is output from the NOT circuit 34, the switching element S ₁ is turned off control.

In the first subtraction unit 36, an assist current value flowing from the values assist current command value I _L ^* to the discharging gain K _S1 or charge gain K _S2 is multiplied to the regenerative current accumulation unit R _A I _L ^* The difference calculation is performed. The first difference signal is PI-controlled by the PI calculation unit 37, and the PWM control unit 38 determines the gate-on time (energization rate) of the switching elements S1, S2.

This gate signal generator 3 controls on / off of only one switching element according to the charge / discharge status of the capacitor C in order to reduce the switching loss in the chopper ch. It is also possible to constitute the gate signal generator 3 so as to switch the switching element S _1, S ₂ alternately.

In the first embodiment, as described above, charging / discharging of the capacitor C is performed by setting a value obtained by multiplying the assist current command value I _L ^* by the discharge gain K _S1 and the charge gain K _S2 as the corrected assist current command value. Suppresses sudden changes in battery current due to stoppage.

A method for determining the discharge gain K _S1 and the charge gain K _S2 will be described in detail based on the gain calculation unit 4 in FIG.

First, in the subtracting unit 41, the capacitor current value I _EDLC is passed through the low-pass filter LPF3 from the value obtained by passing the capacitor voltage V _EDLC through the low-pass filter LPF2 and eliminating the voltage fluctuation due to switching of the switching elements S ₁ and S _2. The capacitor open circuit voltage Vc is calculated by subtracting the value obtained by multiplying the value obtained by removing the current fluctuation by the internal resistance R _EDLC of the capacitor C (that is, the voltage drop due to the internal resistance R _EDLC of the capacitor C). This capacitor open circuit voltage V _C corresponds to the voltage of the capacitor C in an open state in which charging / discharging is not performed. From the capacitor open voltage V _C , capacitor rated voltage V _{EDLC_max,} and battery voltage V _B , the calculation gains K _S1 and charging gain K _S2 are calculated by the following equations (1) and (2) in the calculation units 43a and 43b. Is done.

The discharging gain K _S1 limits the discharging of the capacitor C when the capacitor voltage drops, and the charging gain K _S2 limits the charging of the capacitor C when the capacitor voltage increases. The charging / discharging of the capacitor C by the capacitor voltage V _EDLC can be adjusted by the multiplier N (> 0) in the above equations (1) and (2). The discharging gain K _S1 and the charging gain K _S2 are multipliers. N changes as shown in FIG. 3 (gain change diagram with capacitor open voltage V _C ). That is, when the multiplier N is 0 <N <1, the discharging gain K _S1 and the charging gain K _S2 change exponentially, and when N = 1, the discharging gains K _S1 and K _S2 change proportionally. When 1 <N, the discharging gain K _S1 and the charging gain K _S2 change in a logarithmic function. This multiplier N is arbitrarily set according to various specifications.

Specifically, when the assist current command value I _L ^* ≦ 0 (when discharging), and when the capacitor open circuit voltage V _C is equal to the capacitor rated voltage V _{EDLC_max} , the discharging gain K _S1 calculated by the above equation (1) Becomes 1. In the first embodiment, a value obtained by multiplying the assist current command value I _L ^* by the discharge gain K _S1 is used as a corrected assist current command value for discharging the capacitor C, and the capacitor open circuit voltage V _C is the capacitor rated voltage V _{EDLC_max} . When they are equal, the discharge gain K _S1 = 1, so that the discharge of the capacitor C is not limited. As the capacitor open circuit voltage V _C decreases due to the discharge of the capacitor _C and approaches the battery voltage V _B , the discharging gain K _S1 calculated by the above equation (1) decreases. As the discharge gain K _S1 decreases due to the decrease in the capacitor open voltage V _C , the gate-on time of the switching element (discharge switching element) S ₁ becomes shorter (the conduction ratio becomes lower), and the discharge of the capacitor C is limited. Further, when the capacitor open circuit voltage V _C decreases to the battery voltage V _B due to the discharge of the capacitor C, the discharge gain K _S1 = 0. As a result, the gate of the switching element S ₁ is not turned on, and the discharge of the capacitor C is stopped.

When the assist current command value I _L ^* > 0 (when charging), the charging gain K _S2 calculated by the above equation (2) becomes 1 when the capacitor open voltage V _C is equal to the battery voltage V _B. In the first embodiment, the assist current command value I _L ^* multiplied by the charging gain K _S2 is used as the charge correction assist current command value, and when the capacitor open voltage V _C is equal to the battery voltage V _B , Since the gain K _S2 = 1, the charging of the capacitor C is not limited. As the capacitor open circuit voltage V _C approaches the capacitor rated voltage V _{EDLC_max} due to the charging of the capacitor C, the charging gain K _S2 calculated by the above equation (2) decreases. As the charging gain K _S2 decreases due to the increase in the capacitor open voltage V _C , the gate-on time of the switching element (charging switching element) S ₂ becomes shorter (the conduction ratio becomes lower), and charging of the capacitor C is restricted. Further, when the capacitor open circuit voltage V _C rises to the capacitor rated voltage V _{EDLC_max} due to the charging of the capacitor C, the charging gain K _S2 = 0. As a result, the gate of the switching element S ₂ is not turned on, the charging of the capacitor C is stopped.

Conventionally, when the capacitor voltage V _EDLC is limited, charging / discharging of the capacitor C is suddenly stopped. However, before the capacitor voltage V _EDLC reaches the capacitor rated voltage V _{EDLC_max} as in the first embodiment, by adjusting the charging and discharging, it is possible to suppress an abrupt change of the battery current I _B generated during charge and discharge stop of the capacitor C. As a result, the burden on the battery B is reduced, and the life can be extended.

[Embodiment 2]
In Embodiment 2, discharge gain K _S1a to limit the scope of the capacitor voltage V _EDLC vary by charge and discharge, to change the range of the capacitor voltage V _EDLC applying a charging gain K _S2a. By performing the charge and discharge limitation by state capacitor voltage V _EDLC high range of the capacitor voltage V _EDLC, compared with the case the capacitor voltage V _EDLC is low, the current value at the time of charge and discharge becomes small, the loss due to the internal resistance of the capacitor C Can be suppressed.

In Embodiment 2, the formula used in the first embodiment (1), in place of the equation (2), the capacitor open-circuit voltage V _C, the upper limit voltage value V _{S1_max} discharge limit, the discharge limit lower limit voltage value V _{S1_min,} charge limiting limit of upper limit voltage value V _{S2_max,} the following equation (3) from the lower limit voltage value V _{S2_min} charging limit (4) discharging the gain K _S1a by formula to calculate the charging gain K _S2b, the charge and discharge of the capacitor C To do.

FIG. 4 shows a change characteristic diagram of the gain according to the capacitor open circuit voltage V _C. In the formulas (1) and (2) in the first embodiment, charging / discharging is limited in the capacitor voltage range (V _EDLC ≦ capacitor rated voltage V _{EDLC_max} ) in which charging / discharging is possible in principle. The range of the capacitor voltage V _EDLC to which V is applied is _expressed by the following formulas (3) and (4): V _B ≦ V _{S1_min} (lower limit voltage) <V _{S1_max} (upper limit voltage) (during capacitor C discharge), V _{S2_min} (lower limit voltage) < It is limited to V _{S2_max} (upper limit voltage) ≦ V _{EDLC_max} (when capacitor C is charged). When narrowing the fluctuation range of the capacitor voltage V _EDLC , the lower limit voltage V _{S1_min} of the capacitor discharge limit in the equation (3) is set high, and the upper limit voltage V _{S2_max} of the capacitor charge limit in the equation (4) is set low. Further, when the battery current I _B is suddenly changed when stopping charging and discharging of the capacitor C is discharged adjustment range (V _{S1_min} ~V _{S1_max),} charge adjustment range (V _{S2_min} ~V _{S2_max),} the multiplier N (> 0 adjusted by suppressing the variation of the battery current I _B of).

Specifically, in the second embodiment, when the assist current command value I _L ^* ≦ 0 (during discharge), a value obtained by multiplying the assist current command value I _L ^* by the discharge gain K _S1a is used as the correction assist for the capacitor C discharge. The current command value is used. When the capacitor open voltage V _C is higher than the upper limit voltage V _{S1_max of the} discharge limit as shown in the above equation (3), the discharge gain K _S1a = 1, so the discharge of the capacitor C is not limited. . As the capacitor open circuit voltage V _C decreases due to the discharge of the capacitor _C , falls below the upper limit voltage V _{S1_max} of the discharge limit, and approaches the lower limit voltage V _{S1_min} of the discharge limit, the discharge gain K _S1a calculated by the above equation (3) is Get smaller. As the discharge gain K _S1a decreases due to the decrease in the capacitor open circuit voltage V _C , the gate-on time of the switching element (discharging switching element) S ₁ becomes shorter (the conduction ratio becomes lower), and the discharge of the capacitor C is limited. Further, when the capacitor open circuit voltage V _C decreases to the lower limit voltage V _{S1 — min of the} discharge limit due to the discharge of the capacitor _C , the discharge gain K _S1a = 0. As a result, the gate of the switching element S ₁ is not turned on and the discharge of the capacitor C is stopped.

When the assist current command value I _L ^* > 0 (during charging), when the capacitor open voltage V _C is lower than the lower limit voltage V _{S2_min of the} charging limit, the charging gain K _S2a calculated by the above equation (4) is 1. Become. In the second embodiment, a value obtained by multiplying the assist current command value I _L ^* by the charging gain K _S2a is used as the correction assist current command value for charging the capacitor C, and the capacitor open voltage V _C is the lower limit voltage V of the charging limit. _When it is lower than _{S2_min,} charging gain K _S2a = 1, so charging of capacitor C is not limited. The charging gain K _S2a calculated by the above equation (4) as the capacitor open-circuit voltage V _C increases due to the charging of the capacitor _C , exceeds the lower limit voltage V _{S2_min} of the charging limit, and approaches the upper limit voltage V _{S2_max} of the charging limit. Becomes smaller. As the charging gain K _S2a decreases as the capacitor open-circuit voltage V _C increases, the gate-on time of the switching element (charging switching element) S ₂ becomes shorter (the conduction ratio becomes lower), and charging of the capacitor C is restricted. . Further, when the capacitor C is charged and the capacitor open voltage V _C rises to the upper limit voltage V _{S2 —} max for charging limitation, the charging gain K _S2a = 0. As a result, the gate of the switching element S ₂ is not turned on, the charging of the capacitor C is stopped.

Conventionally, when the capacitor voltage V _EDLC is limited, charging / discharging of the capacitor C is suddenly stopped. However, before the capacitor voltage V _EDLC reaches the capacitor rated voltage V _{EDLC_max} as in the second embodiment, by adjusting the charging and discharging, it is possible to suppress an abrupt change of the battery current I _B generated during charge and discharge stop of the capacitor C. As a result, the burden on the battery B is reduced, and the life can be extended.

In addition, the capacitor voltage V _EDLC range at the time of charging / discharging of the capacitor C is limited and charging / discharging is performed in a state where the capacitor voltage V _EDLC is high as in the second embodiment, so that the capacitor voltage V _EDLC is low. The capacitor current I _EDLC at the time of charging / discharging can be suppressed, and thereby the loss generated by the internal resistance of the capacitor C can be reduced.

[Embodiment 3]
In the third embodiment, in order to omit the current sensor for detecting the capacitor current I _EDLC , the capacitor open voltage V _C is derived not using the capacitor current I _EDLC but using the assist current I _L already detected by the current sensor.

FIG. 5 is a block diagram showing the gain calculation unit 4 according to the third embodiment. Since the configuration other than the gain calculation unit 4 is the same as that of the first and second embodiments, the components other than the gain calculation unit 4 are omitted. It differs from the gain calculating unit 4 in FIG. 2 (Embodiment 1) is in changing the capacitor current I _EDLC of 2 to assist current I _L.

Although the capacitor current I _EDLC fluctuates due to switching of the switching elements S ₁ and S _2, a stable capacitor open voltage V _C can be derived by using the assist current I _L from which the AC component has been removed by the reactor L. It becomes possible.

The calculation units 43a and 43b perform the calculations of the above formulas (1) and (2) (or formulas (3) and (4)) to obtain the discharge gain K _S1 and the charge gain K _S2 (or the discharge gain). The gain K _S1a and the charging gain K _S2a ) are calculated, and charging and discharging are controlled.

Conventionally, when the capacitor voltage V _EDLC is limited, the charging / discharging of the capacitor C is suddenly stopped. However, before the capacitor voltage V _EDLC reaches the rated voltage V _{EDLC_max} as in the third embodiment, the capacitor C it is possible to suppress an abrupt change of the battery current I _B generated during charge and discharge stop of the capacitor C by adjusting the charging and discharging. As a result, the burden on the battery B is reduced, and the life can be extended.

Further, if the calculation gains K _S1a and the charging gain K _S2a are calculated by the calculations of the expressions (3) and (4) in the calculation units 43a and 43b, the capacitor voltage range at the time of charging and discharging the capacitor C is limited. By performing charging / discharging while the voltage V _EDLC is high, the capacitor current I _EDLC can be suppressed as compared with the case where the capacitor voltage V _EDLC is low, thereby reducing the loss generated by the internal resistance of the capacitor C. Is possible.

Furthermore, in the first and second embodiments, a current sensor for detecting the capacitor current I _EDLC is required to limit the capacitor voltage V _EDLC . However, in the third embodiment, the current sensor is not necessary and the cost can be reduced. Become.

[Embodiment 4]
In the fourth embodiment, in the chopper control circuit, a control method in which control by the capacitor voltage V _EDLC is performed instead of multiplying the assist current command value I _L ^* in the first embodiment by the charge / discharge gain is applied. By using this control method, the loss due to the internal resistance of the capacitor C can be reduced by performing charging and discharging while the capacitor voltage V _EDLC is high.

The control of the assist current I _L by the capacitor voltage V _EDLC will be described. FIG. 6 is a block diagram showing a chopper control circuit according to the fourth embodiment. First, the target value V _EDLC ^* of the capacitor voltage V _{EDLC that} changes due to charging / discharging is set, and the second subtraction unit 5 calculates the target value V _EDLC ^* and the capacitor voltage V _EDLC detected by the voltage detector. A difference operation is performed. Since the detected capacitor voltage V _EDLC is superposed by the vibration due to switching of the switching elements S ₁ and S ₂ , the deviation between the target value V _EDLC ^* and the capacitor voltage V _EDLC is taken and then passed through the low-pass filter LPF 5. The PI control unit 6 performs PI control so that there is no deviation. The value (hereinafter referred to as the second difference signal V _{EDLC_DIF} ) is added to the assist current command value I _L ^* used in the chopper control in the adder 7 to output a corrected assist current command value I _L1 ^*, which is the first embodiment. The assist current _IL is controlled in the same manner as described above. The assist current command value I _L ^* is an arbitrary value as in the first embodiment, for example, a value obtained by differentiating the battery voltage V _B and multiplying by the capacitor capacity C _S.

When the capacitor voltage V _EDLC becomes lower than the target value V _EDLC ^* by adding the control of the assist current I _L by the capacitor voltage V _EDLC , the discharge of the capacitor C is limited, and the charging of the capacitor C is promoted. On the contrary, when the capacitor voltage V _EDLC becomes higher than the target value V _EDLC ^* , the charging of the capacitor C is limited and the discharging of the capacitor C is promoted.

That is, when the assist current command value I _L ^* > 0, the capacitor C is controlled to be charged. When the capacitor voltage V _EDLC is lower than the target value V _EDLC ^* , the second difference signal V _{EDLC_DIF} > 0. Thus, a value obtained by adding the second difference signal V _{EDLC_DIF} (> 0) to the assist current command value I _L ^* (> 0) is the corrected assist current command value I _L1 ^* . For this reason, the gate-on time of the switching element S ₂ determined by the PWM method becomes long (the energization rate is high), and the charging of the capacitor C is promoted.

When the assist current command value I _L ^* > 0 and the capacitor voltage V _EDLC is higher than the target value V _EDLC ^* , the second difference signal V _{EDLC_DIF} <0 and the assist current command value I _L ^* (> 0) A value obtained by adding the second difference signal V _{EDLC_DIF} (<0) to the corrected assist current command value I _L1 ^* . Therefore, the gate-on time of the switching element S ₂ determined by the PWM method is shortened (the conduction ratio is low), and charging of the capacitor C is suppressed.

When the assist current command value I _L ^* ≦ 0, the capacitor C is controlled to be discharged. When the capacitor voltage V _EDLC is lower than the target value V _EDLC ^* , the second difference signal V _{EDLC_DIF} > 0. The value obtained by adding the second difference signal V _{EDLC_DIF} (> 0) to the assist current command value I _L ^* (≦ 0) is the corrected assist current command value I _L1 ^* . For this reason, the gate-on time of the switching element S ₁ determined by the PWM method is short (the conduction ratio is low), and the discharge of the capacitor C is suppressed.

When the assist current command value I _L ^* ≦ 0 and the capacitor voltage V _EDLC is higher than the target value V _EDLC ^* , the second difference signal V _{EDLC_DIF} <0, and the second difference to the assist current command value I _L ^* (≦ 0) A value obtained by adding the signal V _{EDLC_DIF} (<0) is the corrected assist current command value I _L1 ^* . For this reason, the gate-on time of the switching element S ₁ determined by the PWM method becomes long (the energization rate is high), and the discharge of the capacitor C is promoted.

When the capacitor voltage V _EDLC is equal to the target value V _EDLC ^* , the second difference signal V _{EDLC_DIF} = 0, so that the assist current command value I _L ^* = corrected assist current command value I _L1 ^* and the capacitor voltage V Control of the assist current by _EDLC is not performed, and charging / discharging of the capacitor C is performed.

Since the control by the capacitor voltage V _EDLC is added to the control of the assist current I _L as in the fourth embodiment, the voltage of the capacitor C can be limited around the target value V _EDLC ^* during charging and discharging. The charging / discharging of the capacitor C suddenly stops and the battery voltage V _B and the battery current I _B do not change suddenly, so that the loss generated in the battery B can be reduced and the life of the battery B can be extended.

Further, by adding a control of the capacitor voltage V _EDLC to control the assist current as in the present embodiment 4, it mainly target value V _EDLC ^* to allow charging and discharging of the capacitor C, the target value V _EDLC ^* Is set high, charging / discharging can be performed in a state where the capacitor voltage V _EDLC is high, and the capacitor current I _EDLC during charging / discharging can be suppressed as compared with the case where the capacitor voltage V _EDLC is low. Thereby, it is possible to reduce the loss generated by the internal resistance of the capacitor C.

[Embodiment 5]
In the fifth embodiment, as in the fourth embodiment, the chopper control circuit uses a control method in which the control is performed using the capacitor voltage V _EDLC instead of multiplying the assist current command value I _L ^* in the first embodiment by the charge / discharge gain. Applied.

In the fourth embodiment, the second difference signal V _{EDLC_DIF} between the target value V _EDLC ^* and the capacitor voltage V _EDLC is added to the assist current I _L ^{*. In the} fifth embodiment, the assist current command value I _L ^* and the assist current are added. The second difference signal V _{EDLC_DIF} is added to the first difference signal I _{L_PWM} obtained by PI control of the difference signal from I _L in the PI calculation unit 37.

When the capacitor voltage V _EDLC becomes lower than the target value V _EDLC ^* by adding the control of the assist current I _L by the capacitor voltage V _EDLC , the discharge of the capacitor C is limited and the charging of the capacitor C is promoted. On the contrary, when the capacitor voltage V _EDLC becomes higher than the target value V _EDLC ^* , the charging of the capacitor C is limited and the discharging of the capacitor C is promoted.

That is, when the assist current command value I _L ^* > 0, the capacitor C is controlled to be charged. When the capacitor voltage V _EDLC is lower than the target value V _EDLC ^* , the second difference signal V _{EDLC_DIF} > The value obtained by adding the second difference signal V _{EDLC_DIF} (> 0) to the first difference signal I _{L_PWM} output from the PI calculation unit 37 becomes the value I _{L_PWM1} output to the PWM control unit 38. For this reason, the gate-on time of the switching element S ₂ determined by the PWM method is long (the energization rate is high), and the charging of the capacitor C is promoted.

When the assist current command value I _L ^* > 0 and the capacitor voltage V _EDLC is higher than the target value V _EDLC ^* , the second difference signal V _{EDLC_DIF} <0, and the first difference signal I _{L_PWM} output from the PI calculation unit 37 A value obtained by adding the two difference signals V _{EDLC_DIF} (<0) is a value I _{L_PWM1} output to the PWM control unit 38. For this reason, the gate-on time of the switching element S ₂ determined by the PWM method is short (the conduction ratio is low), and charging of the capacitor C is suppressed.

Further, when the assist current command value I _L ^* ≦ 0, the capacitor C is controlled to be discharged. When the capacitor voltage V _EDLC is lower than the target value V _EDLC ^* , the second difference signal V _{EDLC_DIF} > The value obtained by adding the second difference signal V _{EDLC_DIF} (> 0) to the first difference signal I _{L_PWM} output from the PI calculation unit 37 becomes the value I _{L_PWM1} output to the PWM control unit 38. For this reason, the gate-on time of the switching element S ₁ determined by the PWM method is short (the conduction ratio is low), and the discharge of the capacitor C is suppressed.

When the assist current command value I _L ^* ≦ 0 and the capacitor voltage V _EDLC is higher than the target value V _EDLC ^* , the second difference signal V _{EDLC_DIF} <0, and the first difference signal I _{L_PWM} output from the PI calculation unit 37 A value obtained by adding the second difference signal V _{EDLC_DIF} (<0) is a value I _{L_PWM1} output to the PWM control unit 38. For this reason, the gate-on time of the switching element S ₁ determined by the PWM method becomes long (the energization rate is high), and the discharge of the capacitor C is promoted.

When the capacitor voltage V _EDLC is equal to the target value V _EDLC ^* , the second difference signal V _{EDLC_DIF} = 0, so that the first difference signal I _{L_PWM} = I _{L_PWM1 and the} assist current I _L is controlled by the capacitor voltage V _EDLC. As a result, the capacitor C is charged and discharged.

Since the control by the capacitor voltage V _EDLC is added to the control of the assist current I _L as in the fifth embodiment, the voltage of the capacitor C can be limited around the target value V _EDLC ^* during charging and discharging. The charging / discharging of the capacitor C suddenly stops and the battery voltage V _B and the battery current I _B do not change suddenly, so that the loss generated in the battery B can be reduced and the life of the battery B can be extended.

Further, as in the fifth embodiment, by adding the control by the capacitor voltage V _EDLC to the control of the assist current, the capacitor C can be _charged / discharged around the target value V _EDLC ^* , and the target value V _EDLC By setting ^* high, charging / discharging can be performed in a state where the capacitor voltage V _EDLC is high, and the capacitor current I _EDLC during charging / discharging can be suppressed compared to when the capacitor voltage V _EDLC is low. Thereby, it is possible to reduce the loss generated by the internal resistance of the capacitor C.

FIG. 3 is a circuit configuration diagram showing a DC power supply of the moving vehicle in the first embodiment. The chopper control block diagram of the DC power supply in Embodiment 1. FIG. FIG. 6 is a gain change diagram according to the capacitor open voltage V _C according to the first embodiment. FIG. 10 is a gain change diagram according to the capacitor open voltage V _C according to the second embodiment. FIG. 9 is a block diagram of a gain calculation unit 4 in the third embodiment. The chopper control block diagram of the DC power supply in Embodiment 4. FIG. 10 is a block diagram of a chopper control for a DC power supply according to a fifth embodiment.

Explanation of symbols

C ... Capacitor ch ... Chopper circuit R _A ... Regenerative current accumulating part B ... Battery V _B ... Battery voltage I _L ^* ... Assist current command value V _EDLC ... Capacitor voltage V _{EDLC_max} ... Capacitor rated voltage K _S1 , K _S1a ... Discharge gain K _S2 , K _S2a ... Charging gain I _EDLC ... Capacitor current value V _C ... Capacitor open-circuit voltage R _EDLC ... Capacitor internal resistance V _{S1_min} ... Discharge limit lower limit voltage V _{S1_max} ... Discharge limit upper limit voltage V _{S2_min} ... Charge limit lower limit voltage V _{S2_max} ... Charging limit upper limit voltage V _EDLC ^* ... Target value

Claims (8)

In a DC power supply in which a regenerative current storage unit having a capacitor and a chopper circuit for stepping up and down the voltage is connected in parallel to the battery,
The first subtraction unit calculates a first difference signal by calculating a difference between an assist current command value flowing through the chopper circuit and an assist current value flowing through the chopper circuit, and the PWM control unit responds to the first difference signal. A chopper control method for generating a gate signal to control a chopper circuit,
A chopper control method for a DC power supply, wherein when the capacitor voltage is equal to or lower than a capacitor rated voltage, the assist current command value or the first difference signal is limited, and a gate signal of the chopper circuit based on the limitation is output. . The limitation applied to the assist current command value is to multiply the assist current command value by a gain,
The gain is calculated from the capacitor open voltage obtained by subtracting the value obtained by multiplying the capacitor current value by the capacitor internal resistance value from the capacitor voltage, the capacitor rated voltage, and the battery voltage in the gain calculation unit. 2. The chopper control method for a DC power supply according to claim 1, wherein the chopper control method is calculated by equation (2).

The limitation applied to the assist current command value is to multiply the assist current command value by a gain,
In the gain calculation unit, the gain includes a capacitor open voltage obtained by subtracting a value obtained by multiplying the capacitor voltage by the capacitor current value and the internal resistance value of the capacitor, and a capacitor discharge limit set in order to narrow the fluctuation range of the capacitor voltage. 2. The DC power supply according to claim 1, wherein the lower limit voltage value and the upper limit voltage value of the capacitor and the lower limit voltage value and the upper limit voltage value of the capacitor charging limit are calculated by the following equations (3) and (4): Chopper control method.

The limitation applied to the assist current command value is to multiply the assist current command value by a gain,
The gain is calculated from the capacitor open voltage obtained by subtracting the value obtained by multiplying the assist current value and the internal resistance value of the capacitor from the capacitor voltage, the capacitor rated voltage, and the battery voltage in the gain calculation unit. 2. The chopper control method for a DC power supply according to claim 1, wherein the chopper control method is calculated by equation (2). The limitation applied to the assist current command value is to multiply the assist current command value by a gain,
In the gain calculation unit, the gain includes a capacitor open voltage obtained by subtracting a value obtained by multiplying the assist current value and the internal resistance value of the capacitor from the capacitor voltage, and a capacitor discharge limit set in order to narrow the fluctuation range of the capacitor voltage. 2. The DC power supply according to claim 1, wherein the lower limit voltage value and the upper limit voltage value of the capacitor and the lower limit voltage value and the upper limit voltage value of the capacitor charging limit are calculated by the above equations (3) and (4). Chopper control method.   The second subtraction unit calculates a second difference signal by performing a difference operation between the capacitor voltage target value and the capacitor voltage value, and the addition unit adds the second difference signal to the assist current command value. A chopper control method for a DC power supply according to claim 1.   The second subtraction unit calculates a second difference signal by performing a difference operation between the capacitor voltage target value and the capacitor voltage value, and the addition unit adds the second difference signal to the first difference signal. A chopper control method for a DC power supply according to claim 1.   A mobile vehicle using the DC power supply chopper control method according to claim 1, wherein the DC power supply is connected to a motor of the mobile vehicle through an inverter capable of regenerative operation.

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