JP5397230B2 - Power control system - Google Patents

Description

  The present invention relates to a power supply control system, and more particularly to control of an inverter circuit having an impedance source of a two-port network in which two inductors and two capacitors are connected in an X shape, that is, a Z-source inverter circuit. It is related with the power supply control system to perform.

  An inverter circuit is known as a circuit for converting DC power into AC power. Also, as a circuit for boosting the power flow voltage to a higher DC voltage, what is called a voltage converter or a booster circuit is known. For example, in order to drive an AC rotating electrical machine using a battery which is a DC power source, an inverter circuit is first required. In this case, if the battery voltage is too low compared with the operating AC voltage of the AC rotating electric machine, a booster circuit that boosts the battery voltage is further required. Thus, in order to drive an AC rotating electrical machine, a power supply circuit including a battery, a booster circuit, and an inverter circuit is generally used.

  Thus, in a power supply circuit including a booster circuit and an inverter circuit, switching control of the booster circuit and switching control of the inverter circuit must be performed. It would be convenient if the DC voltage could be boosted or DC / AC converted with a single switching control.

  Non-Patent Document 1 describes a configuration in which a two-port network in which two inductors and two capacitors are connected in an X shape is used as an impedance source, that is, a Z source, and is arranged between the battery and the inverter circuit. Yes. In this document, an inverter circuit connected to the battery side via a Z source or an impedance network and an inverter circuit connected to the impedance network are called a Z source inverter circuit. Here, it is stated that the inverter circuit may be a general converter circuit, the battery may be a general DC source, and a load or a converter circuit may be connected instead of the battery.

A three-phase inverter circuit is used as the inverter circuit of the Z source inverter circuit, a battery is used as the DC source, and the upper device and the lower device connected in series in each phase arm of the three-phase inverter circuit are turned on. When the period of the zero potential state is T ₀ and one period of switching is T, the on-duty ratio, which is the duty of the through zero potential state, is expressed as D _S = (T ₀ / T), and the battery voltage is expressed as V _0, the voltage value V _i of the DC bus bias the input voltage of the inverter _{circuit, V i = {1 / (} 1-2D S)} V 0 becomes, the _{V 0 B = {1 / (} 1-2D S )} Is stated to be boosted. The maximum output phase voltage of the inverter circuit, using the modulation factor _{M = V ac / (V i} / 2), is also mentioned that, denoted _{V ac = M · B · V} 0/2.

Further, Non-Patent Document 2, the inductor is not the current value I _L through the inductor constant is smaller, is a can be a discontinuous ripple is increased, the current value I _L and the inverter circuit through the inductor It is stated that the relationship with the flowing current value I _i needs to be I _L > (I _i / 2).

  Thus, the Z-source inverter circuit can boost the battery voltage and output an alternating voltage by switching the devices that constitute the inverter circuit. Patent Document 1 discloses the basic contents of Non-Patent Document 1.

  Patent Document 2 describes an inverter device using this Z-source power converter. Here, when a load current that is an output current from the power converter is small, a backflow prevention circuit for a DC power supply is provided. It has been pointed out that if it is provided, the current flowing to the Z source via the backflow prevention circuit becomes zero, and the voltage input to the inverter circuit is reduced to make the operation unstable.

As a technique related to the present invention, Non-Patent Document 3 describes a nonlinear modeling method using a switching flow graph for a converter that performs multi-state switching. Here, in the switching flow graph method, for example, a converter having two switching states is time-divided into two linear sub-circuits, an on-circuit and an off-circuit, and the sub-flow graphs G _ON and G _OFF corresponding thereto are The flow graph G is expressed as a combination of G _ON and G _OFF .

US Patent 7,130,205 Specification JP 2008-67502 A

Fang Zhen Peng et.al., "Z-source Inverter", IEEE Transactions on Industry Applications, vol. 39, No. 2, March / April 2003, p 504-510 Fang Zhen Peng et.al., "Operation Modes and Characteristics of the Z-source Inverter with Small Inductance", IEEE IAS 2005, p 1253-1260 Yonhong Ma et.al., "Switching flow-graph nonlinear modeling method for multistate-switching converters", IEEE Transactions on Power Electronics, vol. 12, No. 5, September 1997, P854-861

As described above, by using the configuration of the Z source inverter circuit, it is possible to perform DC / AC conversion by boosting the DC voltage only by controlling the switching of the devices constituting the inverter circuit. Here, as the operating parameters of the control of the Z source inverter circuit of the prior art, two of both on-duty ratio D _S and the modulation factor M are used. These two operating parameters are not independent of each other, complicating the design of the Z-source inverter circuit.

  As for the control of the Z source inverter circuit, most of the prior art describes the open loop control, and much consideration is not given to the dynamic characteristics. However, if a positive zero appears in the transfer function related to the output voltage, for example, if the input condition changes stepwise, the output voltage will rise sufficiently and the voltage value will drop before moving to the next stable state, etc. An unstable state can occur. In addition, the response delay due to the positive zero makes the control of the inverter circuit complicated and reduces the robustness of the power supply circuit system.

  An object of the present invention is to provide a power supply control system that can further stabilize the operation of a Z-source inverter circuit. Another object is to provide a power supply control system that can have a single operating parameter for the Z source inverter circuit. The following means contribute to at least one of these purposes.

A power supply control system according to the present invention includes a chargeable / dischargeable power storage device, a first inductor disposed between a positive side bus and a negative side bus of the power storage device and arranged in series with the positive side bus, and a negative side bus A second inductor arranged in series; a first capacitor arranged and connected between one end of the first inductor and the other end of the second inductor; and another end of the first inductor and one end of the second inductor An inverter network including a second capacitor disposed between and connected to the impedance network, one side connected to the impedance network, the impedance network as a Z source, and the other side connected to the load device, the positive side bus A plurality of sets of two switching elements connected in series between the negative electrode bus and the negative side bus, and the connection point of the two switching elements of each set is Are connected to respective load devices, boosts the voltage between both terminals of the power storage device by controlling both the on-duty ratio D _S period each set of two switching elements are turned on, the AC power boosted DC power And an inverter circuit that can be supplied to the load device and a control circuit that controls both on-duty ratios D _S of the inverter circuit based on an output voltage command value that is an AC voltage command value output to the load device. The control circuit outputs a feedback output voltage value V _X calculated based on a capacitor voltage value V _C which is a voltage between both terminals of the first capacitor or a voltage value between both terminals of the second capacitor, and an output voltage command value V _Xref. A voltage value subtractor that calculates a voltage deviation ΔV that is a difference between the first inductor and the inductor current command value I that is a command value of a current that flows to the first inductor and the second inductor based on the voltage deviation ΔV. _A current deviation ΔI that is a difference between a current command value calculating means for calculating _Lref , an inductor current value I _L that is a current value flowing through the first inductor or an inductor current value flowing through the second inductor, and an inductor current command value I _Lref. a current value subtracter for calculating a, characterized in that it comprises a duty calculation means for calculating both on-duty ratio D _S of the inverter circuit, a based on the current deviation [Delta] I.

In the power supply control system according to the present invention, the control circuit uses a value calculated by multiplying the capacitor voltage value V _C by a predetermined single operation setting parameter k as the feedback output voltage value V _X. Is preferred.

Further, in the power supply control system according to the present invention, the control circuit, as the operation setting parameters k, based with both the on-duty ratio D _S of the inverter circuit, to the DC terminal voltage of the AC output voltage and the power storage device of the inverter circuit modulation It is preferable to use an operation setting parameter k calculated based on the rate M.

  With the above configuration, the power supply control system includes both an inverter circuit that uses an impedance network as a source, that is, a Z source inverter circuit, and a Z source inverter circuit based on an output voltage command value that is a command value of an AC voltage output to the load device. And a control circuit for controlling the on-duty ratio.

Then, the control circuit feeds back the feedback output voltage value V _X calculated based on the capacitor voltage value V _C to the output voltage command value V _Xref and calculates the voltage deviation ΔV. Further, the inductor current command value I _Lref is calculated based on the voltage deviation ΔV, and the inductor current value I _L is fed back to this to calculate the current deviation ΔI. Both the on-duty ratio D _S of the inverter circuit is required to the current deviation to zero. Thus, since both on-duty ratios D _S of the Z source inverter circuit are obtained using voltage feedback and current feedback, the operation stability of the Z source inverter circuit is improved.

Further, the feedback output voltage value V _X is obtained as kV _C. That is, in the Z source inverter circuit of the prior art, were required two parameter settings D _S and M, where can those operating parameters Z source inverter circuit for a single. Therefore, the control of the Z source inverter circuit can be simplified.

The operation setting parameter k is calculated based on _DS and M. That is, since the operation setting parameter k, which is a combination of the two conventional parameters, is used, the control of the Z source inverter circuit can be simplified.

It is a figure explaining the structure of the power supply control system of embodiment which concerns on this invention. It is a figure explaining the equivalent circuit of Z source inverter circuit. In the Z source inverter circuit, it is a diagram for explaining an equivalent circuit in the both-on state. FIG. 10 is a diagram for explaining an equivalent circuit in a normal operation state mode in which both of the Z source inverter circuits are not on. FIG. 6 is a diagram for explaining a state of a control signal in a normal operation state mode in which both are not turned on in the Z source inverter circuit. FIG. 6 is a diagram for explaining a state of a control signal in an operation state mode in which both are on in a Z source inverter circuit. It is a figure explaining the small signal model of Z source inverter circuit. It illustrates a simplified equivalent circuit including a D _S and M of Z source inverter circuit. It is a figure explaining the control block diagram of the feedback of Z source inverter circuit in the power supply control system of an embodiment concerning the present invention. It is a control block diagram of the power supply control system of the embodiment according to the present invention. One of simulation result of the power control system according to the embodiment of the present invention, V _DC is a diagram showing a state of a V _i when changes stepwise. It is a figure which shows the mode of _{Vac on} the same conditions of _VDC change as FIG. It is a figure which shows the mode of I _{load on} the same conditions of _VDC change as FIG. FIG. 12 is a diagram illustrating a state of V _i under the same condition of _VDC variation as in FIG. 11 in a power supply control circuit including a Z-source inverter circuit of a conventional technique. FIG. 12 is a diagram illustrating a state of V _ac under the same _VDC variation condition as in FIG. 11 in a power supply control circuit including a Z-source inverter circuit according to a conventional technique. FIG. 12 is a diagram illustrating a state of I _load under the same _VDC change condition as that in FIG. 11 in a power supply control circuit including a Z-source inverter circuit according to a conventional technique. It is one of the simulation results about the power supply control system of embodiment which concerns on this invention, and is a figure which shows the mode of a change of _Iload as what changed the load stepwise. Under the terms of the same load changes 17 is a diagram showing a state of V _i. It is a figure which shows the mode of _{Vac on} the same load change conditions as FIG. FIG. 18 is a diagram illustrating how I _load changes as the same load change as in FIG. 17 in a power supply control circuit including a conventional Z-source inverter circuit. FIG. 18 is a diagram illustrating a state of V _i under the same load change condition as in FIG. 17 in a power supply control circuit including a Z-source inverter circuit according to a conventional technique. FIG. 18 is a diagram illustrating a state of V _ac under the same load change condition as in FIG. 17 in a power supply control circuit including a conventional Z-source inverter circuit.

  Embodiments according to the present invention will be described below in detail with reference to the drawings. In the following, a rotating electrical machine mounted on a vehicle will be described as a load device, but it may not be a vehicle mounting device, and may not be a rotating electrical machine. The load device may be any device that uses a power supply circuit system that needs to boost DC power and convert it to AC.

  Below, the same code | symbol is attached | subjected to the same element in all the drawings, and the overlapping description is abbreviate | omitted. In the description in the text, the symbols described before are used as necessary.

  FIG. 1 is a diagram illustrating a configuration of a power supply control system 10 connected to a rotating electrical machine 8 mounted on a vehicle. The power supply control system 10 is a system that controls a power supply circuit that boosts DC power and converts it into AC in accordance with the operating state of a vehicle-mounted rotating electrical machine 8 that is a load device.

  Here, the on-vehicle rotating electrical machine 8 is a motor / generator (MG) mounted on the vehicle and functions as a motor when power is supplied from a power supply circuit, and is driven by an engine (not shown). Alternatively, it is a three-phase synchronous rotating electric machine that functions as a generator during braking of a vehicle.

  The power supply control system 10 includes a power storage device 12, an impedance network 14, an inverter circuit 16 using the impedance network 14 as a Z source network, and a control circuit 20.

  The power storage device 12 is a chargeable / dischargeable high voltage secondary battery. As the power storage device 12, for example, a lithium ion assembled battery or a nickel hydride assembled battery having a terminal voltage of about 200 V, a capacitor, or the like can be used.

  The impedance network 14 is a Z source network for the inverter circuit 16 with the impedance represented as Z. Impedance network 14 is disposed between the positive and negative buses of 12 of the power storage device, and includes a first inductor 22 arranged in series with the positive bus and a second inductor arranged in series with the negative bus. 24, a first capacitor 26 disposed and connected between one end of the first inductor 22 and the other end of the second inductor 24, and the other end of the first inductor 22 and the second inductor 24. And a second capacitor 28 disposed between and connected to one end of the capacitor.

  The inverter circuit 16 is a circuit connected to the rotating electrical machine 8 mounted on the vehicle, and includes a plurality of switching elements that operate under the control of the control circuit 20, and converts power between AC power and DC power. It has a function to perform. Here, it is a three-phase inverter circuit corresponding to the three-phase synchronous rotating electric machine 8. That is, each phase arm in which two switching elements are connected in series is arranged and connected between the positive side bus and the negative side bus, and a diode is reversely connected to each switching element.

  As the two switching elements constituting each phase arm, for example, a p-type IGBT (Insulated Gate Bipolar Transistor) connected to the positive-side bus side and an n-type IGBT connected to the negative-side bus side may be used. it can. Then, each phase wiring is drawn out from the connection point of the p-type IGBT and the n-type IGBT in each phase arm and connected to each phase winding of the rotating electrical machine 8.

  When the rotating electrical machine 8 functions as a generator, the inverter circuit 16 has an AC / DC conversion function that converts AC three-phase regenerative power from the rotating electrical machine 8 into DC power and supplies it as a charging current to the power storage device 12 side. . In addition, when the rotating electrical machine 8 functions as a motor, it has a quadrature conversion function that converts DC power from the power storage device 12 side to AC three-phase driving power and supplies the AC power to the rotating electrical machine 8 as AC driving power.

  Here, the inverter circuit 16 is connected not to a voltage source such as a normal voltage converter but to the impedance network 14 on the DC power source side opposite to the rotating electrical machine 8 that is a load device. In the conventional technique in which the DC voltage source side is a normal voltage converter, changing the degree of voltage conversion is performed by controlling the switching timing of the switching elements constituting the voltage converter. On the other hand, the impedance network 14 does not include a switching element.

In the Z source inverter circuit that combines the impedance network 14 and the inverter circuit 16, the switching timing of the switching elements of the inverter circuit 16 is controlled in order to boost the DC voltage of the power storage device 12. Specifically, in the inverter circuit 16, to control both the on-duty ratio D _S corresponding to a period for turning on both the two switching elements connected in series between the positive side bus bar and the negative bus, the power storage The DC voltage of the device 12 is boosted. Details thereof will be described later.

The control circuit 20 has a function of controlling these elements as a whole, but in this case, in particular, has a function of performing control for improving the operation stability of the Z source inverter circuit. Specifically, after simplifying the operating parameters of the Z-source inverter circuit, voltage feedback and current feedback are performed, and the output voltage command value that is the command value of the AC voltage output to the rotating electrical machine 8 that is the load device is set. Based on this, the inverter circuit 16 has a function of controlling both on-duty ratios D _S.

  As will be described later, the control circuit 20 is provided with a current closed loop and a voltage closed loop in order to further stabilize the operation of the Z source inverter circuit. Before describing the contents, the contents of the power supply circuit including the Z source inverter circuit shown in Non-Patent Documents 1 and 2 will be described with reference to FIGS.

2 to 4 are diagrams for explaining the operation of the Z source inverter circuit. FIG. 2 is an equivalent circuit of a Z-source inverter circuit in which the inverter circuit 16 is a model having an input voltage value V _i and an input current value I _i . Here, the power storage device 12 is shown as V _DC , the first inductor 22 is shown as L ₁ , the second inductor 24 is shown as L ₂ , the first capacitor 26 is shown as C ₁ , and the second capacitor 28 is shown as C _2. Has been. The input side of the inverter circuit 16 is equivalently modeled as a voltage value V _i and a current value I _i .

  As described above, the impedance network 14 of the Z source inverter circuit includes the first inductor 22 arranged and connected to the positive side bus, and the second inductor 24 arranged and connected to the negative side bus. The first capacitor 26 and the second capacitor 28 are arranged and connected between the positive-side bus bar and the negative-side bus bar, as if they are struck against the arrangement relationship of the two inductors 24.

Here, when the impedance network 14 is configured symmetrically, L ₁ = L ₂ = L and C ₁ = C ₂ = C. The currents flowing through the two inductors 22 and 24 are equal, and the voltages across the terminals of the two capacitors 26 and 28 are also equal.

  FIG. 3 is an equivalent circuit when at least one of the phase arms constituting the inverter circuit 16 is both on. Here, the inverter circuit 16 is shown as being short-circuited. FIG. 4 is an equivalent circuit when both of the phase arms constituting the inverter circuit 16 are not turned on, that is, in a general operation state. Here, the inverter circuit 16 is shown as a current source. Yes.

  The Z-source inverter circuit is characterized by positively utilizing the both-on state in which two series-connected switching elements constituting each phase arm are both turned on. Etc. will be described.

  FIG. 5 is a diagram illustrating an operation state of a general inverter circuit that does not use the both-on state, and FIG. 6 is a diagram illustrating an operation state of the inverter circuit when the both-on state is used. In these figures, the horizontal axis represents time, and the amplitude or on / off state of each signal is shown in the vertical axis direction.

  Each signal arranged in the vertical axis direction is a triangle wave signal used for PWM (Pulse Wide Modulation) control from the upper side to the lower side on the paper surface, and the p-type IGBT on / off of each phase arm of the inverter circuit 16. An off signal is an on / off signal of an n-type IGBT.

V _a ^* , V _b ^* , and V _c ^* shown to intersect with the triangular wave signal correspond to each phase output signal of PWM control, and p-type IGBT and n-type of each phase arm at this intersection timing. The IGBT is turned on / off. For example, the three phases are a-phase, b-phase, and c-phase, respectively, and the on / off of the p-type IGBT and n-type IGBT of the a-phase arm is determined by the intersection of V _a ^* and the triangular wave signal. In the example of FIG. 5, in the time zone when V _a ^* exceeds the triangular wave signal, the a-phase arm p-type IGBT on / off signal S _ap is turned off and the n-type IGBT on / off signal _San is turned on. . Similarly, the magnitude relation between V _b ^* and the triangular wave signal, b-phase arm of the p-type IGBT, the on-off of n-type IGBT is determined, the magnitude relationship between the V _c ^* and the triangular wave signal, a c-phase arm On / off of the p-type IGBT and the n-type IGBT is determined.

  Thus, in the case of FIG. 5, when either one of the p-type IGBT and the n-type IGBT constituting each phase arm of the inverter circuit 16 is turned on, the other is turned off, and both are not turned on. As a result, no through current flows in each phase arm. The operation state of a general inverter circuit is used in such an operation mode. On the other hand, in the operation mode shown in FIG. 6, a p-type IGBT and an n-type IGBT constituting each phase arm of the inverter circuit 16 are both turned on.

For example, the period in which on-off signal S _ap of p-type IGBT of a phase arm is turned on, there is a portion that overlaps with the period in which n-type IGBT on and off signal S _an, is turned on. In FIG. 6, the overlapping state is indicated by hatching in the lowermost stage, and the portion for the a-phase arm is indicated by filling. As described above, when one cycle of the on / off signal of each phase arm is T, there is a period T _{0 in} which both are turned on and a period T _{1 in} which both are not turned on. Here, T = T ₀ + T ₁ , and the on-duty ratio D _S can be expressed as D _S = T ₀ / T.

  Since the Z-source inverter circuit actively uses the both-on state, the states of FIGS. 3 and 4 exist. As a nonlinear modeling method using a switching flow graph for a converter that performs multi-state switching as described above, the method of Non-Patent Document 3 is known. FIG. 7 shows a small signal model of the Z source inverter circuit using the method of Non-Patent Document 3.

Here, V _C is a capacitor voltage value which is a voltage between both terminals of the first capacitor 26 or a voltage value between both terminals of the second capacitor 28. V _DC is a voltage between both terminals of the power storage device 12. _IL is an inductor current value that is a current value flowing through the first inductor or an inductor current value flowing through the second inductor. I _i is a direct current that flows between the impedance network 14 and the inverter circuit 16, and corresponds to an input current to the inverter circuit 16 when viewed from the power storage device 12 side. D _S is the above-described on-duty ratio, and D _N is a duty ratio corresponding to a period in which both are not on, and D _N = 1−D _S.

Using small signal model of FIG. 7, when obtaining the various transfer functions relating D _S in the power supply circuit including a Z source inverter circuit, comprising the formula (1) and (3). Equation (1) is a transfer function for V _i / D _S , Equation (2) is a transfer function for V _C / D _S , and Equation (3) is a transfer function for I _L / D _S.

From equation (1), it can be seen that there is a zero at which the numerator is zero in the transfer function for V _i / D _S , and that zero can be positive. Therefore, it can be seen that under certain conditions, the system of the power supply circuit including the Z source inverter circuit becomes unstable and difficult to control.

From equation (2), it can be seen that a positive zero does not appear in the transfer function for V _C / D _S , and therefore, instability does not occur in that sense. However, as shown in Non-Patent Document 2, if L ₁ and L ₂ are small, a positive zero may appear when I _i > 2I _{L. In} this case, transmission is performed in a certain operation mode. The function becomes unstable and the operation becomes unstable.

  When a positive zero appears in the transfer function related to the output voltage of the impedance network 14, its dynamic characteristics are degraded, and overshoot or undershoot becomes remarkable. As a result, a step-like transient characteristic appears in the input voltage to the inverter circuit 16. This influence is also reflected in the AC output voltage of the inverter circuit 16, and overshoot or undershoot appears in the output voltage to the rotating electrical machine 8 that is the load device.

As described above, when viewed from the transfer function with respect to the on-duty ratio D _S , the operation of the power supply circuit including the Z source inverter circuit may become unstable depending on conditions. The power supply control system 10 in FIG. 1 includes an inner current closed loop and an outer voltage closed loop in the control circuit 20, and uses proportional integral control (PI control) or proportional differential integral control (PID control) to provide a Z source. The operation of the power supply circuit including the inverter circuit is further stabilized. The contents will be described below.

The purpose of designing the control circuit 20 is to limit the position of the equilibrium state relative to the target output. The target outputs of the power supply circuit including the Z source inverter circuit are the capacitor voltage value V _C in the impedance network 14 and the AC output voltage value V _X output from the inverter circuit 16. Of the two parameters in the Z-source inverter circuit described in the prior art, the on-duty ratio D _S mainly controls the capacitor voltage value V _C , and the modulation factor M mainly controls the output voltage value V _X. To do.

Here, as described above, the on-duty ratio D _S is expressed as D _S = T ₀ / T, where T is a switching cycle of each phase arm and T ₀ is a period during which both phases are on. It is. Further, when the input voltage in the inverter circuit 16 is V _i and the amplitude of the output AC voltage is V _ac , the modulation factor M is expressed by M = V _ac / (V _i / 2).

The equivalent circuit incorporating with both on-duty ratio D _S and the modulation factor M shown in FIG. Here, the on / off duty of the switch S ₁ indicates the on-duty ratio D _S, and the on / off duty of the switch S ₂ indicates the modulation factor M. Here, Formula (4) can be used as a condition.

Capacitor voltage value V _C is given by V _C = {T ₁ / (T ₁ −T ₀ )} by distinguishing one switching period T into both ON period T ₀ and other period T ₁ as described above. It is done. This is transformed using D _S = T ₀ / T to obtain equation (5).

Here, the input voltage value V _i of the inverter circuit 16 is a difference voltage between the capacitor voltage value V _C and the inductor voltage value V _L due to the configuration symmetry of the impedance network 14. That is, V _i = V _C −V _L. In addition, V _L is a voltage difference between the terminal voltage V _DC of the power storage device 12 and the capacitor voltage value V _C , and therefore V _L = V _DC −V _C. Therefore, V _i = V _C −V _L = 2V _C −V _DC . If V _C = {T ₁ / (T ₁ −T ₀ )} is applied to this, V _i = {T / (T ₁ −T ₀ )} V _DC .

That is, the voltage V _DC between the terminals on the power storage device 12 side of the impedance network 14 is boosted to the voltage value V _i on the inverter circuit 16 side by using the both-on state of the inverter circuit 16. The boost ratio B, which is the boost ratio, is B = {T / (T ₁ −T ₀ )}.
The AC output voltage value V _X of the inverter circuit 16 is given by V _X = M · B (V _DC / 2) using the modulation factor M and the boost ratio B. It becomes.

Expression (7) is derived from Expressions (4), (5), and (6).

From this equation (7), equation (8) can be defined.

From this equation (8), if the characteristics of the Z source inverter circuit are expressed by the relationship between the capacitor voltage value V _C and the AC output voltage value V _X , the operation setting parameters can be aggregated into a single k. I understand. That is, when V _X = kV _C , k is a predetermined single operation setting parameter, and this operation setting parameter k is an inverter based on the equations (5), (6), (8). it can be calculated based on the both the on-duty ratio D _S of the circuit 16, to the modulation factor M of the inverter circuit 16.

Here, returning to Equation (3), a positive zero does not appear in the transfer function for I _L / D _S. Therefore, it is expected that the power supply control system 10 can be stably operated by performing linear PI control or PID control. However, as described above, it is pointed out from the expression (2) that a positive zero may appear in the transfer function for V _C / D _S when I _i > 2I _L. From these facts, it is considered that the control circuit 20 should perform PI control or PID control using a closed loop of current inside the main loop of control and provide a closed loop of voltage outside.

  Here, the inner current closed loop enables a high-speed response, and an effect of stabilizing the output against current disturbance can be expected. Further, the outer voltage closed loop can be expected to stabilize low-speed fluctuations and improve the followability to the command value.

FIG. 9 is based on the above idea, and in the power supply circuit that outputs the output voltage value V _X by giving the output voltage command value V _Xref , the operation is stabilized by using the inner current closed loop and the outer voltage closed loop. FIG. 2 shows a block diagram of control to be performed.

In FIG. 8, a portion surrounded by a square frame is a block diagram regarding an inner current closed loop. As shown in FIG. 8, the actually measured capacitor voltage value V _C is used as a feedback signal, and the inductor current value I _L is used as a disturbance signal. The transfer function related to V _i / D _S in this block diagram is obtained as shown in Equation (9).

This new equation is different from the equation (1) when the current closed loop is not provided, and the instability due to the zero point is removed. However, there is a possibility that the operation becomes unstable when I _i > 2I _L. By the way, the open loop transfer function regarding the open loop I _L / D _S for the inner current loop is given by Equation (10).

Since equation (10) does not have instability due to zeros, it is not so difficult to stabilize it. As shown in FIG. 9, the inner current loop is a closed loop using PI control or PID control indicated by the gain G _i .

In FIG. 9, in order to stabilize the output voltage value V _X , it is necessary to change the command current value with respect to the input voltage. The simplest way to accomplish this is to provide an outer voltage loop. The voltage deviation ΔV generated between the output voltage value V _X fed back by the voltage loop and the output voltage command value V _Xref is used as the inductor current command value I _Lref in the inner current loop.

Here, the feedback output voltage value V _X can be calculated from the capacitor voltage value V _C using the single operation setting parameter k as described in the equation (8). The output voltage value V _X calculated in this way is used to make the outer voltage loop a closed loop, as shown in FIG.

From the block diagram of FIG. 9, the transfer function related to V _i / I _L is obtained as Equation (11).

  It can be seen that this new transfer function operates stably because it does not have a positive zero.

  Thus, as shown in the block diagram of FIG. 9, the control circuit 20 is preferably provided with an inner current closed loop and PI control or PID control, and with an outer voltage closed loop.

FIG. 10 is a diagram illustrating a specific block diagram of the power supply control system 10 including an inner current closed loop and an outer voltage closed loop. Here, the impedance network 14, a voltage detector 30 for detecting the capacitor voltage value V _C, the current detector 32 for detecting the inductor current I _L is provided.

  In FIG. 10, the voltage detector 30 detects the voltage between both terminals of the first capacitor 26, but of course, the voltage detector 30 may detect the voltage value between both terminals of the second capacitor 28. In addition, the current detector 32 detects the inductor current value flowing through the second inductor 24, but of course, the current detector 32 may detect the inductor current value flowing through the first inductor 22.

10, the control circuit 20, in accordance with the output voltage command value V _Xref, as a main loop for determining the D _S for the inverter circuit 16, a voltage value subtractor 44, a PI controller 46, a current value subtracter 48 And a PI controller 50.

A parameter k setting unit 42 for converting the capacitor voltage value V _C detected by the voltage detector 30 in the impedance network 14 into the output voltage value V _X is provided. As described above, the parameter k setting unit 42 calculates k based on the equations (5), (6), and (8) from _DS and M corresponding to the operating state of the rotating electrical machine 8 that is the load device. It is a computing unit.

The voltage value subtractor 44 is the difference between the feedback output voltage value V _X calculated by multiplying the capacitor voltage value V _C acquired by the voltage detector 30 by the operation setting parameter k and the output voltage command value V _Xref. This is an arithmetic unit having a function of calculating the voltage deviation ΔV. Here, the voltage deviation ΔV is ΔV = V _Xref −V _x . That is, the feedback output voltage value V _X calculated by multiplying the capacitor voltage value V _C by the operation setting parameter k is fed back to the output voltage command value V _Xref .

The PI controller 46 is an arithmetic processing unit having a function of calculating an inductor current command value I _Lref for making the voltage deviation ΔV zero by PI control. Here, the PI control function is used, but it is of course possible to use a PID control function.

The current value subtractor 48 has a function of calculating a current deviation ΔI that is a difference between the inductor current value I _L acquired by the current detector 32 and the inductor current command value I _Lref output by the PI controller 46. It is an arithmetic unit. Here, the current deviation ΔI is ΔI = I _Lref −I _L. That is, the inductor current I _L is fed back to the inductor current command value I _Lref.

PI controller 50, the PI control is an arithmetic processor having a function of calculating both on-duty ratio D _S for the current deviation ΔI and zero. Here, the PI control function is used, but it is of course possible to use a PID control function.

Calculated D _S is inputted to the PWM control circuit 52. The PWM control circuit 52, the triangular wave signal is used as described in FIG. 6, PWM phase output signals V _a ^* or the like corresponding to the D _S is outputted. The output PWM phase signal is supplied to the inverter circuit 16 via the drive circuit 54. From the inverter circuit 16, the AC output voltage V _X is actually supplied to the rotating electrical machine 8 that is a load device.

The result of calculating the operation of the above configuration by simulation will be described with reference to FIGS. Here, FIGS. 11 to 16 show simulation results when _VDC changes stepwise, and FIGS. 17 to 22 show simulation results when the load changes stepwise. 11 to FIG. 16, FIGS. 11 to 13 are based on the configuration of FIGS. 1 and 10, and FIGS. 14 to 16 are based on the configuration of the prior art. Similarly, in FIGS. 17 to 22, FIGS. 17 to 19 are based on the configuration of FIGS. 1 and 10, and FIGS. 20 to 22 are based on the configuration of the prior art.

FIG. 11 is a diagram illustrating a state of V _i when V _DC changes in a step shape in the configuration of FIGS. The step change in V _DC, at time 0.12 s, was that suddenly changed from 100V to 60V. It can be seen from FIG. 11 that overshoot and undershoot are suppressed at V _i that is the output voltage of the impedance network 14 against such a sudden change in V _DC .

FIG. 12 is a diagram showing a state of V _ac under the same condition of _VDC change as FIG. V _ac is the AC output voltage of each phase of the inverter circuit 16, and FIG. 12 shows the state of the output voltage waveform for each of the three phases. As shown in FIG. 12, it can be seen that the influence of the step-like change in V _DC is well suppressed in V _{ac at} time 0.12 s.

FIG. 13 is a diagram illustrating the state of I _load under the same condition of _VDC change as in FIG. I _load is each phase current corresponding to each phase voltage in FIG. As shown in FIG. 13, it can be seen that at time 0.12 s, the influence of the step-like change in V _DC is well suppressed in I _load .

  14 to 16 show a power supply control circuit including a conventional Z-source inverter circuit, that is, in the case where neither an inner current closed loop nor an outer voltage closed loop is provided using open loop control. FIG.

FIG. 14 is a diagram showing the state of V _i under the same _VDC variation condition as described in FIG. 11 in the prior art, and corresponds to FIG. As shown in FIG. 14, in the power supply control circuit including the Z-source inverter circuit of the prior art, V _i overshoot occurs at time 0.12 s, and the influence of the step change of _VDC is remarkable. It can be seen that

FIG. 15 is a diagram showing the state of V _{ac in} the prior art under the same _VDC variation condition as in FIG. 11, and corresponds to FIG. As shown in FIG. 15, in the conventional technique, the fluctuation of the output voltage value V _ac of each phase occurs at time 0.12 s, and the influence of the step change of _VDC appears remarkably. I understand.

FIG. 16 is a diagram showing the state of I _{load in} the prior art under the same condition of _VDC change as in FIG. 11, and corresponds to FIG. As shown in FIG. 16, in the conventional technique, when the time is 0.12 s, the I _load of each phase fluctuates, and it can be seen that the influence of the step change of _VDC appears remarkably. .

FIG. 17 is a diagram illustrating a state in which I _load is changed in a step shape from 40A to 120A as a response to the step change in the load state in the configuration of FIGS.

FIG. 18 is a diagram showing a state of V _i under the same load change condition as FIG. As shown in FIG. 19, it can be seen that V _i slightly fluctuates at time 0.12 s. FIG. 19 is a diagram showing the state of V _ac under the same load change condition as FIG. As shown in FIG. 20, it can be seen that V _ac slightly fluctuates at time 0.12 s. Thus, even if the load state changes stepwise, it can be seen that in the configurations of FIGS. 1 and 10, the fluctuations in V _i and V _ac are well controlled.

  20 to 22 show a power supply control circuit including a conventional Z-source inverter circuit, that is, in the case where neither an inner current closed loop nor an outer voltage closed loop is provided using open loop control. FIG.

FIG. 20 is a diagram corresponding to FIG. 17 and is a diagram illustrating a state in which I _load is changed from 40A to 120A in a step shape as corresponding to the step change of the load state in the configuration of the related art. .

FIG. 21 is a diagram showing the state of V _i under the same load change condition as in FIG. 17 in the conventional technique. As shown in FIG. 21, it can be seen that undershoot of V _i occurs at time 0.12 s, and the influence of the change in the step-like load state appears remarkably. FIG. 22 is a diagram showing the state of V _{ac in} the conventional technique under the same load change condition as FIG. As shown in FIG. 22, it can be seen that at time 0.12 s, V _ac fluctuates greatly, and the influence of the change in the step-like load state appears remarkably.

  As described above, by using the configuration of the power supply control system 10 described with reference to FIGS. 1 and 10, a stable control operation can be performed as compared with a power supply control circuit including a conventional Z-source inverter circuit.

  The power supply control system according to the present invention can be used to control a power supply circuit including a Z source inverter circuit.

  8 rotating electrical machines, 10 power supply control systems, 12 power storage devices, 14 impedance networks, 16 inverter circuits, 20 control circuits, 22, 24 inductors, 26, 28 capacitors, 30 voltage detectors, 32 current detectors, 42k setting devices, 44 voltage value subtractor, 46, 50 PI controller, 48 current value subtractor, 52 PWM control circuit, 54 drive circuit.

Claims (3)

A chargeable / dischargeable power storage device;
A first inductor disposed between a positive electrode bus and a negative electrode bus of the power storage device and disposed in series with the positive electrode bus, a second inductor disposed in series with the negative electrode bus, one end of the first inductor, and the first inductor An impedance network including a first capacitor arranged and connected between the other end of the two inductors and a second capacitor arranged and connected between the other end of the first inductor and one end of the second inductor;
An inverter circuit in which one side is connected to an impedance network, the impedance network is used as a Z source, and the other side is connected to a load device, and two switching elements connected in series between a positive side bus and a negative side bus Including a plurality of sets, the connection points of the two switching elements of each set are connected to the load device, respectively, and both ends of the power storage device are controlled by controlling both on-duty ratios D _S during a period in which the two switching elements of each set are both turned on. An inverter circuit that boosts the voltage between the children, converts the boosted DC power into AC power, and supplies it to the load device;
A control circuit that controls both on-duty ratios D _S of the inverter circuit based on an output voltage command value that is a command value of an AC voltage output to the load device;
With
The control circuit
This is the difference between the feedback output voltage value V _X calculated based on the capacitor voltage value V _C which is the voltage between both terminals of the first capacitor or the voltage value between both terminals of the second capacitor, and the output voltage command value V _Xref. A voltage value subtractor for calculating the voltage deviation ΔV;
Current command value calculating means for calculating an inductor current command value I _Lref that is a command value of a current flowing through the first inductor and the second inductor based on the voltage deviation ΔV;
A current value subtractor that calculates a current deviation ΔI that is a difference between an inductor current value I _L that is a current value that flows through the first inductor or an inductor current value that flows through the second inductor, and an inductor current command value I _Lref ;
A duty calculation means for calculating both on-duty ratio D _S of the inverter circuit based on the current deviation [Delta] I,
A power supply control system comprising: The power supply control system according to claim 1,
The control circuit
A power supply control system using a value calculated by multiplying a capacitor voltage value V _C by a single predetermined operation setting parameter k as the feedback output voltage value V _X. The power supply control system according to claim 2,
The control circuit
As the operation setting parameters k, is used with both the on-duty ratio D _S of the inverter circuit, the operation setting parameter k is calculated based on the modulation factor M based on the voltage between the DC terminals of the AC output voltage and the power storage device of the inverter circuit A power supply control system characterized by that.

Images