Transformer control device and solenoid valve drive device

Abstract

The variable voltage control device of the present invention is a variable voltage control device for a variable voltage chopper circuit that outputs a variable voltage by turning on / off the current with a switch. In the variable voltage chopper circuit, when the main switch that is turned on when the inductor stores energy is in the on state, the output voltage is taken in, and at least the on / off of the main switch is controlled.

Description

[0001] This application claims the priority of Japanese Patent Application No. 2020-164527 filed on September 30, 2020, and incorporates its content herein. Technical Field

[0002] The present invention relates to a voltage conversion control device and a solenoid valve drive device. Background Art

[0003] In Japanese Unexamined Patent Application Publication No. 2012-158985, a boost control process for a boost circuit that outputs a desired target voltage (DC voltage) to the outside is disclosed. This boost control process is as Figure 3 described, by the CPU detecting the output terminal voltage (actual boost voltage) of the boost circuit to which the smoothing capacitor is connected, and adjusting the duty ratio in the on / off control of the first switch according to this actual boost voltage, feedback control is performed on the boost circuit so that the actual boost voltage becomes the target voltage.

[0004] The above boost circuit is a voltage conversion circuit that turns on / off the second switch synchronously with the first switch, accumulates the charge released from the coil in the smoothing capacitor, and thus realizes the boosting of the input voltage. That is, in the boost circuit, when the first switch is in the on state and the second switch is in the off state, the charge (energy) based on the input voltage is accumulated in the coil, and then by switching the first switch to the off state and the second switch to the on state, the charge accumulated in the coil is used to charge the smoothing capacitor.

[0005] The above CPU detects the terminal voltage of the smoothing capacitor as the actual boost voltage, but when the internal resistance of the smoothing capacitor is relatively large, the actual boost voltage slowly reaches the final voltage according to the time constant defined by the capacitance and internal resistance value of the smoothing capacitor. That is, the actual boost voltage does not reach the final voltage instantaneously, but reaches the final voltage with a delay based on the time constant. Therefore, there is a possibility of an error in the detected value of the actual boost voltage depending on at which timing the actual boost voltage is taken into the CPU, and this error can cause a deviation from the target voltage. Summary of the Invention

[0006] The present invention has been completed in view of the above circumstances, and an object thereof is to provide a voltage conversion control device with less deviation from the target voltage than in the past.

[0007] Means for Solving the Problems

[0008] The first mode of the voltage conversion control device of the present invention is a voltage conversion control device of a voltage conversion chopper circuit that outputs a converted voltage by turning on / off a current with a switch. The voltage conversion control device takes in the output voltage input from the voltage conversion chopper circuit during a period when the main switch that is turned on when the inductor stores energy is in the on state and the sub-switch is in the off state in the voltage conversion chopper circuit, and at least controls the on / off of the main switch. In the voltage conversion chopper circuit, the sub-switch that is turned on when charging a smoothing capacitor according to the energy of the inductor is a synchronous switch that turns on / off in the opposite manner to the main switch.

[0009] In the second mode of the voltage conversion control device of the present invention, in the above first mode, the sub-switch is a diode.

[0010] In the third mode of the voltage conversion control device of the present invention, in any one of the above first to second modes, the voltage conversion chopper circuit is a boost chopper circuit or a bidirectional buck-boost chopper circuit.

[0011] The first mode of the solenoid valve drive device of the present invention includes a voltage conversion control device in any one of the above first to third modes; and a drive device that drives a solenoid valve with a boosted output using this voltage conversion control device.

[0012] In the second mode of the solenoid valve drive device of the present invention, in the above first mode, the solenoid valve is a fuel injection valve provided in an engine.

[0013] Effects of the Invention

[0014] According to the present invention, a voltage conversion control device with less deviation from the target voltage than in the past can be provided. Description of the Drawings

[0015] Figure 1 It is a block diagram showing the overall structure of an injector drive device according to an embodiment of the present invention.

[0016] Figure 2 It is a timing chart showing the operation of an injector drive device according to an embodiment of the present invention.

[0017] Figure 3 It is a timing chart showing the effects of an injector drive device according to an embodiment of the present invention.

[0018] Figure 4 It is a block diagram showing the overall structure of an injector drive device according to a modified example of an embodiment of the present invention.

[0019] Figure 5 It is a block diagram showing the overall structure of an injector drive device according to a modified example of an embodiment of the present invention. Detailed Description of the Invention

[0020] Hereinafter, with reference to the accompanying drawings, an embodiment of the present invention will be described.

[0021] The injector driving device 5 (driving device 5) of this embodiment is a solenoid valve driving device 5 that drives the Figure 1 shown injector L as a load, and includes a boost chopper circuit 1, a driving circuit 2, and a control unit 3. At the input end of the injector driving device 5, battery power supply with a specified voltage (battery voltage) is supplied from an external battery. This battery power is supplied to the boost chopper circuit 1 and the driving circuit 2 as shown in the figure.

[0022] The injector L is a fuel injection valve (solenoid valve) that is equipped in an engine as is well known, and injects fuel into the engine. By using an electromagnet, the needle valve is movable to switch the fuel injection / non-injection. Such an injector L supplies power to the coil constituting the electromagnet through the driving current supplied from the injector driving device 5, and sets the needle valve to the closed valve state / open valve state. That is, such an injector L is classified as an inductive load (also called an inductive load) among various well-known loads.

[0023] The boost chopper circuit 1 is a type of step-up chopper circuit that transforms the input by turning the current on / off through well-known chopper control and then outputs it. That is, the boost chopper circuit 1 is a power conversion circuit that converts (boosts) the battery power (input power) of the first voltage into DC power (output power) of a voltage higher than the first voltage, that is, the second voltage, and outputs it to the injector L. Such a boost chopper circuit 1 has a shunt resistor 1a, an inductor 1b, a main switch 1c, a synchronous switch 1d, and a smoothing capacitor 1e as shown in the figure.

[0024] One end of the shunt resistor 1a is connected to the input end of the injector driving device 5, and the other end is connected to one end of the inductor 1b. This shunt resistor 1a is a resistor with a relatively small resistance value, and generates a voltage drop corresponding to the passing current for the input power. One end and the other end of such a shunt resistor 1a are connected to the control unit 3. That is, the voltage between the terminals of the shunt resistor 1a is output from the boost chopper circuit 1 to the control unit 3.

[0025] One end of the inductor 1b is connected to the other end of the above-mentioned shunt resistor 1a, and the other end is connected to the input end of the main switch 1c and the input end of the synchronous switch 1d. In this inductor 1b, if the main switch 1c becomes in the on state (conducting state), a current (inductor current) due to the input power is applied, and if the main switch 1c is switched from the on state to the off state (non-conducting state), the electromagnetic energy due to the decay change of the inductor current is accumulated.

[0026] The input terminal of the main switch 1c is connected to the other end of the inductor 1b and the input terminal of the synchronous switch 1d, the output terminal is grounded, and in addition, the control terminal is connected to the control unit 3. That is, the output terminal of the main switch 1c is connected to GND which is the reference potential. This main switch 1c is an electronic switch that switches between the on state (conductive state) and the off state (non-conductive state) by the first boost control signal input from the control unit 3, and turns on when accumulating electromagnetic energy in the inductor 1b. As shown in the figure, such a main switch 1c is, for example, a MOS-FET (MOS type field effect transistor).

[0027] The input terminal of the synchronous switch 1d is connected to the other end of the inductor 1b and the input terminal of the main switch 1c, the output terminal is connected to one end of the smoothing capacitor 1e and the input terminal of the drive circuit 2, and in addition, the control terminal is connected to the control unit 3. This synchronous switch 1d is a sub-switch that turns on / off contrary to the main switch 1c and is controlled by the second boost control signal input from the control unit 3. Such a synchronous switch 1d is, for example, a MOS-FET (MOS type field effect transistor) like the above-mentioned main switch 1c.

[0028] In addition, in order to prevent through-current, the discontinuous timing of the main switch 1c and the discontinuous timing of the synchronous switch 1d are slightly staggered.

[0029] One end of the smoothing capacitor 1e is connected to the output terminal of the synchronous switch 1d and the input terminal of the drive circuit 2, and the other end is grounded. That is, the other end of the smoothing capacitor 1e is connected to GND which is the reference potential. One end of such a smoothing capacitor 1e corresponds to the output terminal of the boost chopper circuit 1 and is connected to the control unit 3 as shown in the figure. That is, the output voltage of this boost chopper circuit 1 is output to the control unit 3 as the boost voltage.

[0030] Among the pair of input terminals of the drive circuit 2, one is connected to the output terminal of the boost chopper circuit 1, and the other is connected to the input terminal of the injector drive device 5. In addition, the output terminal of this drive circuit 2 is connected to one end of the injector L, and the control input terminal is connected to the control unit 3. Such a drive circuit 2 has a plurality of on-off switches that operate according to the drive control signal input to the control input terminal from the control unit 3, and supplies a drive current of a desired waveform to the injector L by alternately selecting boost power (boost output) and battery power (non-boost output) and applying it to the injector L.

[0031] The control unit 3 is a control device that controls the above boost chopper circuit 1 and drive circuit 2, and generates the above first boost control signal, second boost control signal, and drive control signal according to a prescribed control program. That is, this control unit 3 is a software control device that synthesizes hardware resources and software resources, and at least has an input / output circuit for exchanging signals with the boost chopper circuit 1 and drive circuit 2, a storage device for storing control information such as the control program, and an arithmetic device for executing the control program. This control unit 3 is preferably a software control device that synthesizes hardware resources and software resources, but it may also be controlled by hardware only.

[0032] As a functional structural element realized through the cooperation of hardware resources and software resources, such a control unit 3 has a current detection unit 3a, a voltage detection unit 3b, a boost control unit 3c, and a drive control unit 3d as shown in the figure. In addition, among these respective structural elements, the current detection unit 3a, voltage detection unit 3b, and boost control unit 3c constitute a boost control device. This boost control device corresponds to the voltage conversion control device 4 of the present invention.

[0033] One pair of input terminals of the current detection unit 3a are respectively connected to one end and the other end of the shunt resistor 1a. This current detection unit 3a detects the current flowing through the shunt resistor 1a, that is, the input current of the boost chopper circuit 1, as a boost current based on the voltage between the terminals of the shunt resistor 1a and the resistance value of the shunt resistor 1a stored in advance, and outputs this boost current to the boost control unit 3c.

[0034] The input terminal of the voltage detection unit 3b is connected to the output terminal of the boost chopper circuit 1 and the input terminal of the drive circuit 2. This voltage detection unit 3b detects the output voltage of the boost chopper circuit 1 as a boost voltage and outputs it to the boost control unit 3c.

[0035] The boost control unit 3c is a controller that feedback-controls the boost chopper circuit 1. Among the pair of output terminals of this boost control unit 3c, one is connected to the control terminal of the main switch 1c, and the other is connected to the control terminal of the synchronous switch 1d.

[0036] Such a boost control unit 3c adjusts the drive of the boost chopper circuit 1 according to the boost current input from the current detection unit 3a and the boost voltage input from the voltage detection unit 3b, so that the boost voltage follows a desired target voltage. That is, this boost control unit 3c has a current control function and a voltage control function, and controls the boost chopper circuit 1 to output a boost power with a boost voltage that matches the target voltage.

[0037] More specifically, the boost control unit 3c controls the boosting of the boost chopper circuit 1 by adjusting the first boost control signal (pulse signal) output to the main switch 1c, and controls the on / off state of the synchronous switch 1d corresponding to the on / off state of the main switch 1c by generating a second boost control signal (pulse signal) that turns on / off in a phase opposite to that of the first boost control signal. Additionally, PWM control can also be used as the first boost control signal. In this case, the boost ratio of the boost chopper circuit 1 is controlled by adjusting the duty ratio of the pulse signal.

[0038] The drive control unit 3d is a controller that controls the drive circuit 2. This drive control unit 3d supplies a drive current of a desired waveform to the drive circuit 2 by controlling the on / off states of a plurality of opening / closing switches included in the drive circuit 2. Additionally, this drive control unit 3d and the above-described boost control unit 3c are uniformly controlled by an upper control system (not shown).

[0039] Next, with reference to Figure 2 and Figure 3 the operation of the injector drive device 5 of the present embodiment will be described in detail. Additionally, this injector drive device 5 is a device that performs a boosting operation and a drive operation, but since it has a feature in the boosting operation, the boosting operation will be mainly described below.

[0040] Figure 2 Part (a) shows the on / off operation of the main switch 1c, Figure 2 Part (b) shows the on / off operation of the synchronous switch 1d, Figure 2 Part (c) shows the synchronous current flowing through the synchronous switch 1d when the synchronous switch 1d is in the on state, Figure 2 Part (d) shows the time variation of the output of the boost chopper circuit 1, i.e., the boost voltage. As shown in part (a) of this Figure 2 the main switch 1c turns on / off at a prescribed timing, and as shown in Figure 2 part (b), the synchronous switch 1d turns on / off in a phase opposite to the on / off of the main switch 1c. As shown in Figure 2 part (d), the boost chopper circuit 1 boosts the battery voltage at a prescribed boost ratio and outputs a boost voltage.

[0041] Here, in Figure 2 part (d), it shows the state after the boost control unit 3c has performed control to drive the boost chopper circuit 1 to increase the boost voltage before the illustrated time range. In this state, as shown in the figure, the boost voltage slowly increases and approaches the target voltage Vref, and reaches the target voltage Vref at time tp, for example.

[0042] However, in the boosted voltage, a current ripple caused by the synchronous current is superimposed as shown in the figure. The boosted voltage is generated by the charging current flowing in the smoothing capacitor 1e due to the electromagnetic energy stored in the inductor 1b in the boost chopper circuit 1. The original waveform is a gentle curve as shown by the dashed-dotted line.

[0043] That is, the target voltage Vref of the boosted voltage at time tp is caused by the current ripple. The original boosted voltage at time tp is a value of the voltage deviation ΔV lower than the target voltage Vref. This voltage deviation ΔV is the control deviation in the control of the boost chopper circuit 1, and the boosted voltage is adjusted to a value lower than the target voltage Vref by the voltage deviation ΔV.

[0044] For such a situation, the boost control unit 3c in the present embodiment takes in the boosted voltage input from the boost chopper circuit 1 during the period when the current ripple is avoided. That is, the boost control unit 3c avoids the period when the synchronous switch 1d is on, that is, takes in the boosted voltage during the period when the synchronous switch 1d is off.

[0045] By such an operation of taking in the boosted voltage by the boost control unit 3c, the influence of the current ripple can be excluded. Therefore, according to the present embodiment, it is possible to provide the injector drive device 5 (or the transformer control device 4) with a smaller deviation from the target voltage Vref than in the past.

[0046] Here, Figure 3 The (a) part of is the drive current waveform when the drive circuit 2 supplies power to the injector L. In this drive current waveform, the rising period T1 is the waveform part generated when the drive circuit 2 continuously applies the boosted voltage (boost power) to the injector L. In contrast, the holding period T2 is the waveform part generated when the drive circuit 2 intermittently applies the battery voltage (battery power) to the injector L.

[0047] In addition, the (b) part of the figure is a timing chart showing the correspondence between the power supply voltage and the drive current during power supply. Furthermore, Figure 3 The (c) part of is a timing chart showing the correspondence between the lift amount of the needle valve in the injector L and the drive current.

[0048] As Figure 2 shown in the (d) part of, when the boosted voltage is set (adjusted) to a value of the voltage deviation ΔV lower than the target voltage Vref, as Figure 3 shown in the (a) part of, the time when the drive current becomes the maximum peak value during the rising period T1 is delayed as shown by the dashed-dotted line compared to the original time shown by the solid line considering the influence of the current ripple. This delay is such that Figure 3The main reason why the moment when the lift amount of the needle valve in the injector L shown in part (c) becomes maximum is delayed from time ta to time tb.

[0049] This is because the opening of the needle valve is generated when the current supplied to the injector L reaches a specified value. Then, the delay of this lift amount from time ta to time tb causes a deviation from the target amount of fuel injected into the engine. That is, a deviation from the target voltage Vref of the boost voltage causes a control deviation in the engine control.

[0050] In the present embodiment, the influence of current ripple can be excluded, and it is not necessary to adjust the boost voltage to a value lower than the target voltage Vref by the voltage deviation ΔV. Therefore, since the deviation from the target voltage Vref of the boost voltage can be suppressed compared with the prior art, the control deviation in the engine control can be suppressed compared with the prior art. Therefore, according to the present embodiment, an engine control with excellent controllability can be achieved.

[0051] In addition, the present invention is not limited to the above embodiment, and for example, the following modification examples are considered.

[0052] (1) In the above embodiment, the case of reducing the voltage deviation ΔV related to the boost voltage of the boost chopper circuit has been described, but the present invention is not limited thereto. The present invention can also be applied to reducing the voltage deviation related to the buck voltage of the buck circuit or the voltage deviation ΔV related to the boost voltage and the buck voltage of the bidirectional boost-buck circuit.

[0053] For example, in the injector drive device 5, there is a type in which the regenerative current based on the back electromotive force of the injector L charges (regenerates) the battery via the drive circuit and the bidirectional boost-buck circuit. As Figure 4 shown, such an injector drive device 5a has a bidirectional boost-buck chopper circuit 6A, a drive circuit 2A, and a control unit 3A.

[0054] The bidirectional boost-buck chopper circuit 6A is a power converter that performs a buck operation in addition to the boost operation, and is a transformer chopper circuit in which a smoothing capacitor 1f is added between one end of the shunt resistor 1a and GND for the boost chopper circuit 1. In addition to the boost operation as the above boost-buck circuit, the bidirectional boost-buck chopper circuit 6A steps down the regenerative power input from the drive circuit 2A and outputs it to the battery by switching the functions of the main switch 1c and the synchronous switch 1d. In such a buck operation, the synchronous switch 1d is turned on when the inductor 1b stores electromagnetic energy.

[0055] That is, during the period when the main switch 1c that acts as an auxiliary switch is turned off, the voltage detection unit 3e of the control unit 3A takes in the voltage at one end of the smoothing capacitor 1f, i.e., the step-down voltage, and outputs it to the boost control unit 3f. Then, the boost control unit 3f adjusts the drive of the synchronous switch 1d that acts as the main switch so that the step-down voltage becomes the desired step-down target voltage. Additionally, Figure 1 Similarly, Figure 4 the current detection unit 3a, the voltage detection unit 3e, and the boost control unit 3f constitute a boost control device. This boost control device corresponds to the voltage conversion control device 4a of the present invention. Additionally, the injector drive device 5a is a solenoid valve drive device 5a that drives the injector L as a load.

[0056] (2) In the above-described embodiment, the boost chopper circuit 1 having the synchronous switch 1d as an auxiliary switch has been described, but the present invention is not limited thereto. As Figure 5 shown, instead of the synchronous switch 1d, a diode 1g whose anode terminal is connected to the inductor 1b and the input terminal of the main switch 1c, and whose cathode terminal is connected to one end of the smoothing capacitor 1e and the input terminal of the drive circuit 2 can be used as the auxiliary switch.

[0057] In the injector drive device 5b Figure 5 shown in this way, since a boost chopper circuit 7A having a diode 1g as a passive element is used instead of the synchronous switch 1d as an active element, a control unit 3B having a boost control unit 3g that only controls the main switch 1c is used instead of the boost control unit 3c. Additionally, the above-described diode 1g autonomously performs on / off operations in the same manner as the synchronous switch 1d according to the voltages of the anode terminal and the cathode terminal. Additionally, Figure 1 Similarly, Figure 5 the current detection unit 3a, the voltage detection unit 3b, and the boost control unit 3g constitute a boost control device. This boost control device corresponds to the voltage conversion control device 4b of the present invention. Additionally, the injector drive device 5b is a solenoid valve drive device 5b that drives the injector L as a load.

[0058] (3) In the above-described embodiment, MOS-FETs are used in the main switch 1c and the synchronous switch 1d, but the present invention is not limited thereto. For example, IGBTs (Insulated Gate Bipolar Transistors) can also be used.

[0059] Reference Numeral Explanation

[0060] L Injector

[0061] 1 Boost Chopper Circuit

[0062] 1A Bidirectional Buck-Boost Circuit

[0063] 1a Shunt Resistor

[0064] 1b Inductor

[0065] 1c Main Switch

[0066] 1d Synchronous Switch (Auxiliary Switch)

[0067] 1e, 1f Smoothing Capacitor

[0068] 2, 2A Drive Circuit

[0069] 3, 3A Control Unit

[0070] 3a Current Detection Unit

[0071] 3b, 3e Voltage Detection Unit

[0072] 3c, 3f Boost Control Unit

[0073] 3d Drive Control Unit.

Claims

1. A variable voltage control device is a variable voltage control device for a chopper circuit that steps up or down an input by turning a switch on and off to output the stepped-up or down voltage. It is characterized in that the variable voltage control device takes in the output voltage input from the output terminal of the chopper circuit during the period when the main switch that is turned on when the inductor stores energy in the chopper circuit is in the on state and the sub-switch is in the off state, and controls the on / off of the main switch. In the chopper circuit, the sub-switch that is turned on when charging the smoothing capacitor according to the energy of the inductor is a synchronous switch that turns on and off in the opposite manner to the main switch. One end of the inductor is connected to the input voltage, the other end is connected to the input terminal of the main switch and the input terminal of the sub-switch, the output terminal of the main switch is grounded, and the output terminal of the sub-switch is connected to the smoothing capacitor.

2. The variable voltage control device according to claim 1, characterized in that the sub-switch is a diode.

3. The variable voltage control device according to claim 1 or 2, characterized in that the chopper circuit is a boost chopper circuit or a bidirectional buck-boost chopper circuit.

4. A solenoid valve driving device, characterized in that, Comprising: the variable voltage control device according to claim 1 or 2; and a driving device that uses the boosted output of the variable voltage control device to drive a solenoid valve.

5. An electromagnetic valve driving device, characterized in that, Comprising: the variable voltage control device according to claim 3; and a driving device that uses the boosted output of the variable voltage control device to drive a solenoid valve.

6. The solenoid valve driving device according to claim 4, characterized in that the solenoid valve is a fuel injection valve provided in an engine.

7. The solenoid valve driving device according to claim 5, characterized in that the solenoid valve is a fuel injection valve provided in an engine.

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