JP5152501B2 - Load control device and electrical equipment - Google Patents

Description

  The present invention relates to a load control device having a power factor correction circuit for converting an input voltage into a DC voltage boosted by a switching operation of a switching element, and an electric apparatus including the load control device.

  Generally, a lighting device, which is a load control device including an inverter circuit, lights a lamp at a constant brightness by controlling the switching frequency of the switching means or the switching duty ratio according to the lighting state of the lamp and the power supply voltage. It is configured to be able to.

  In recent years, with the development of various digital devices, digital control of lighting devices is increasing in order to control the lighting devices from digitized external devices. In this case, it is common to digitize the control device that controls the drive of the inverter circuit. By digitizing the control device in this way, it becomes easier to obtain desired control characteristics and control with quick response is possible. I can expect.

  A digital signal processing device (DSP), which is a digitized control device, generates a PWM signal to be supplied to the inverter circuit by digital arithmetic processing. In such digital arithmetic processing, the power supply voltage, the lighting state of the lamp, and the like are detected, a PWM signal is generated in response to this detection, and is input to the inverter circuit, for example, the lamp lighting frequency and the output voltage are turned on. The lamp is lit stably by controlling the duty.

In such a lighting device, for example, a boost chopper circuit may be used as a power factor correction circuit (PFC circuit), and a power supply unit that boosts a power supply voltage by the boost chopper circuit may be used. Such a power supply unit includes a comparator that compares a predetermined reference voltage with a voltage generated by the detected lamp current, and a drive circuit that generates a PWM signal (switching pulse) to be supplied to the switching element in accordance with an output from the comparator. The switching element is switched by the PWM signal generated by this drive circuit, thereby enabling boost chopping (see, for example, Patent Document 1).
JP 2003-36991 A (page 3-5, FIG. 1)

  However, in the lighting device described above, the minimum ON width of the output PWM signal is determined by the response time of the comparator and the like. In particular, when the power supply unit is operated in the critical mode, the switching frequency of the switching element depends on the hardware. Therefore, the minimum on-duty is automatically determined from the minimum on-width of the PWM signal, and is limited to a predetermined output or less. For example, when the load is light, there is a problem that the output DC voltage rises if this critical mode is continued.

  The present invention has been made in view of these points, and an object of the present invention is to provide a load control device that can suppress an increase in output DC voltage even when the load is light, and an electrical device including the load control device.

The load control device of claim 1, wherein is provided with a first switching element, the power factor correction circuit and for converting the DC voltage obtained by boosting the input voltage by the switching operation of the first switching element; inputting a dimming signal from the outside A dimming signal section; comprising a second switching element; the DC voltage converted by the power factor correction circuit is converted by the switching operation of the second switching element and output to light the load; and input to the dimming signal section a lighting circuit for dimming the load in response to the dimming signal; and controlling the switching operation of the first switching element, the critical mode and the discontinuous current mode the operating mode of the power factor correction circuit in accordance with at least the dimming signal And switching means for switching between and.

  The power factor correction circuit is a boost chopper circuit, for example, and can be switched between a critical mode and a current discontinuous mode.

  The load is preferably a low-pressure mercury discharge lamp such as a fluorescent lamp, but is not limited thereto.

As the lighting circuit, for example, a half-bridge type inverter circuit including a pair of switching elements is used, but the lighting circuit is not limited to this.

Switching means, for example, as a predetermined signal, using a No. tone Mitsunobu lamp as a load, it switches the operation mode of the power factor correction circuit in the critical mode and a current discontinuous mode in accordance with these.

  According to a second aspect of the present invention, there is provided an electrical apparatus comprising: the load control device according to the first aspect; and a load controlled by the load control device.

According to the load control device of the first aspect, the switching unit switches the operation mode of the power factor correction circuit between the critical mode and the current discontinuous mode according to at least the dimming signal input to the dimming signal. When the load is light, the increase in the output DC voltage can be suppressed by switching to the current discontinuous mode.

  According to the electric device according to claim 2, by providing the load control device according to claim 1, it is possible to suppress an increase in the output DC voltage even when the load is light.

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

  Fig. 1 is a circuit diagram of the load control device, Fig. 2 is a bottom view showing a cross section of a part of the electric equipment provided with the load control device, and Fig. 3 (a) is a critical mode of the power factor correction circuit of the load control device. FIG. 3 (b) is a graph showing the operation in the current discontinuous mode of the power factor correction circuit of the load control device.

  As shown in FIG. 2, a ceiling-embedded lighting fixture 11 that is a lighting fixture as an electric device is a ceiling-embedded lighting fixture that is installed on a system ceiling in which, for example, T bars are assembled in a grid shape. As a discharge lamp (discharge lamp), that is, a quadrangular annular lamp 12 is used as a polygonal annular lamp. The lamp 12 is, for example, a lamp having a tube diameter of 15 mm to 18 mm, and has a quadrangular annular shape having four straight sides 13 and four corners 14 that connect the ends of the four sides 13 at substantially right angles. The arc tube 15 is formed, and has a base 16 that connects both ends of the arc tube 15 at the center of one side of the arc tube 15 and has a coldest part formed in the vicinity thereof. Connection pins (not shown) connected to electrodes (not shown) provided at both ends of the arc tube 15 are projected.

  Then, the ceiling-embedded lighting fixture 11 has a fixture main body 21 as a device main body, and the fixture main body 21 is formed in a quadrangular box shape with an open bottom surface. A side plate portion 24 bent downward from the peripheral edge portion of the top plate portion 23 and a frame portion 25 bent in a substantially L shape around the lower end of the side plate portion 24 are provided. The outer dimension of the frame portion 25 of the instrument main body 21 is formed to be smaller than the inner dimension of the embedded opening surrounded on all sides by the T-bar of the system ceiling.

  A square-shaped opening 26 is formed in the central region of the top plate 23, and the lower surface side of the opening 26 can be attached to the lower surface of the ceiling plate 23 by screws or the like. It is attached.

  Between the top plate portion 23 and the side plate portion 24 of the fixture main body 21 and the side surface portion 33 of the ceiling-attached equipment attachment body 31, a quadrangular annular lamp accommodating portion 37 having an open lower surface is formed. A lamp 12 is accommodated.

  In addition, on the lower surface of the top plate portion 23 of the fixture body 21, the lighting device mounting portion 23a that is a load control device mounting portion that is an edge portion of one side of the opening portion 26 is provided at one end along the edge portion of the opening portion 26. A discharge lamp lighting device 42 (hereinafter referred to as a lighting device 42) as a load control device having a power input side 40 and a lamp output side terminal 41 arranged at the other end is attached. A power terminal block 43 is attached to the edge of the side that intersects with one side of the opening 26 to which the lighting device 42 is attached, and the lamp output side terminal 41 of the lighting device 42 has the opening 26 to which the power terminal block 43 is attached. A lamp socket 44 that is also used as a lamp holder that attaches the base 16 of the lamp 12 to the edge of the side opposite to the side and detachably holds the base 16 of the lamp 12 is attached. The lighting device 42 and the power terminal block 43 are disposed inside the ceiling-attached facility attachment body 31 and are covered together with the opening 26.

  In the lighting device 42, as shown in FIG. 1, an inverter circuit 52 is connected to a power supply unit 51 as a power factor correction circuit that rectifies and smoothes a commercial AC power supply e. The filaments FLa and FLb of the lamp 12 are connected via a circuit 53. In addition, a preheating circuit 55 for the filaments FLa and FLb of the lamp 12 is connected to a connection portion between the inverter circuit 52 and the resonance circuit 53. Further, a digital signal processing device 56 (hereinafter referred to as DSP 56), which is a circuit control means as a control device, is connected to the power supply unit 51, the inverter circuit 52, and the preheating circuit 55. Further, a dimming signal unit 57 for inputting a dimming signal DIM from the outside is connected to the DSP 56. The commercial AC power source e, the power source 51, the inverter circuit 52, the resonance circuit 53, the preheating circuit 55, the DSP 56, the dimming signal unit 57, and the like constitute a lighting circuit 58 as an operating circuit. And the lamp 12 are connected to form a main circuit 59.

  The power supply unit 51 is a step-up chopper power supply as a power factor correction (PFC) circuit that can switch between a so-called critical mode and a current discontinuous mode that match the phases of the input current I0 and the input voltage V0, and is a commercial AC power supply. A full-wave rectifier element REC1 is connected to e, and a boost chopper circuit 60 is connected to the output side of the full-wave rectifier element REC1. In the boost chopper circuit 60, a series circuit of a chopper choke L1 that is a boosting transformer and a reverse blocking diode D1 is connected to the output side of the full-wave rectifying element REC1 and the inverter circuit 52. A first switching element as a switching element, that is, a field effect transistor (FET) Q1, which is a chopping switching element, is connected in parallel to the connection point between the chopper choke L1 and the anode of the diode D1, and the cathode of the diode D1 The electrolytic capacitor C1, which is a smoothing capacitor, is connected in parallel to the connection point between the inverter circuit 52 and the inverter circuit 52.

  The chopper choke L1 has a primary winding L1a and a secondary winding L1b, and the primary winding L1a is connected between the output side of the full-wave rectifying element REC1 and the anode of the diode D1, and the secondary winding L1a One end of the winding L1b is connected to the ground potential, and the other end is connected to the DSP 56 via the detection resistor R1. Accordingly, the DSP 56 receives the choke voltage V generated in the resistor R1 by the choke current I from the secondary winding L1b of the chopper choke L1.

  In the field effect transistor Q1, the drain terminal is connected to the connection point between the chopper choke L1 and the anode of the diode D1, the source terminal is connected to the ground potential via the resistor R2, and the gate terminal is the control terminal. Is connected to the DSP 56 via the drive element 61.

  Here, the drive element 61 turns on / off the field effect transistor Q1 in accordance with the chopping PWM signal PC as the PWM control signal supplied from the DSP 56 (switching driving), thereby allowing the field effect transistor Q1 of the boost chopper circuit 60 to be switched. Between the drain and the source at high speed.

  The inverter circuit 52 is a so-called half-bridge type in which field effect transistors Q2 and Q3, which are switching elements for inverters as second switching elements, are connected in series to the power supply unit 51.

  The gate terminals of the field effect transistors Q2 and Q3 are connected to the DSP 56 via a high side driver 65 as control means, and on / off is controlled by a signal supplied from the high side driver 65.

  The high-side driver 65 alternately turns on and off the field effect transistors Q2 and Q3 at a frequency of about several tens of kHz to 200 kHz, for example, 50 kHz or more in the present embodiment, according to the dimming PWM signal P supplied from the DSP 56 By doing (switching driving), a predetermined high-frequency alternating current is generated between the drain and source of the field effect transistor Q3.

  In the resonance circuit 53, a resonance capacitor C4 is connected in parallel between both ends of the field effect transistor Q3 via a capacitor C3 that cuts off a DC component and a resonance winding (resonance inductor) L2 in series.

  The preheating circuit 55 includes a series circuit of a preheating transformer L3, a capacitor C5, a field effect transistor Q4 as a preheating switching element and a resistor R4 for current detection, and a connection point between the capacitor C5 and the field effect transistor Q4 and a field effect. A diode D2 is connected between the source terminal of the transistor Q2.

  In the preheating transformer L3, the primary winding L3a, the first secondary winding L3b and the second secondary winding L3c are arranged to face each other, and the primary winding L3a is a connection point between the field effect transistors Q2 and Q3. And the resonance capacitor C4, and the secondary windings L3b and L3c are connected to the filaments FLa and FLb of the lamp 12 via the capacitors C6 and C7, respectively.

  In the field effect transistor Q4, a gate terminal as a control terminal is connected to the DSP 56, and switching control is performed by a preheating PWM signal supplied from the DSP 56.

  The DSP 56 is an MPU (arithmetic element) such as a so-called microcomputer that performs digital signal processing. The DSP 56 performs switching of the switching unit 71 as switching means connected to the chopper booster circuit 60 and switching of the field effect transistor Q4 of the preheating circuit 55. Preheating circuit control unit 72 for controlling, the operating state of the lighting circuit 58 and the lamp 12 by detecting at least one of the discharge current, that is, the lamp current IL and the discharge voltage, that is, the lamp voltage VL (the operating state of the main circuit 59) A state detection unit 73 having a function of state detection means for detecting the signal, and a signal for generating a PWM signal P for controlling the operation of the field effect transistors Q2 and Q3 of the inverter circuit 52 based on the operation state detected by the state detection unit 73 A dimming signal generation unit 74 that is an inverter circuit control unit as a generation unit, and a dimming signal that detects the dimming signal DIM from the dimming signal unit 57 A dimming signal detection unit 75 as a signal detection unit is integrally provided therein, and a ROM, a RAM, an I / O port as an interface, etc. (not shown) are provided.

  Note that the DSP 56 integrally includes the switching unit 71, the preheating circuit control unit 72, the dimming signal generation unit 74, the dimming signal detection unit 75, and the like means that these share the software processing part in the DSP 56. .

  The switching unit 71 converts the input voltage V0, the DC output voltage V1, the choke voltage V, and the switching current ID flowing through the field effect transistor Q1, which are analog signals, into digital frequency data corresponding to them. D-converter function, A / D converted input voltage V0, DC output voltage V1, choke voltage V, switching current ID, dimming signal DIM output from dimming signal detector 75, etc. The chopping PWM signal PC, which is a switching pulse of the field effect transistor Q1, is generated based on the predetermined signal and output to the drive element 61.

  That is, the switching unit 71 generates a chopping PWM signal PC, which is a control signal for performing feedback control so that the DC output voltage V1 approaches a desired target value, based on the rectified power supply voltage waveform serving as the reference waveform SW. Is set as follows. The reference waveform SW can be varied corresponding to at least one of the DC output voltage V1 (output current I1) from the inverter circuit 52 and the power supply voltage, for example.

  Here, the switching unit 71 can switch the operation mode of the power supply unit 51 between the critical mode shown in FIG. 3A and the current discontinuous mode shown in FIG. This switching includes the operation switching point included in the dimming signal DIM output from the dimming signal unit 57, the switching current ID flowing through the input voltage V0 and the field effect transistor Q1, and the DC output voltage V1 from the power supply unit 51. It is performed according to at least one of the following.

  When the switching unit 71 switches the operation mode of the power supply unit 51 according to the operation switching point included in the dimming signal DIM, for example, when the dimming level is set to be greater than a predetermined dimming level by the dimming signal DIM The power supply unit 51 is operated in the critical mode, and the power supply unit 51 is operated in the current discontinuous mode when the dimming signal DIM is set to a dimming level equal to or lower than a predetermined dimming level.

  Further, when the switching unit 71 switches the operation mode of the power supply unit 51 according to the input voltage V0 and the switching current ID, for example, the input voltage V0 and the switching current ID are respectively set to predetermined voltage thresholds set in advance. Compared with the current threshold value, the power supply unit 51 is operated in the critical mode when at least one of the threshold values is larger than the threshold value, and the power supply unit 51 is operated in the current discontinuous mode when smaller than each threshold value. To do.

  Further, when the switching unit 71 switches the operation mode of the power supply unit 51 in accordance with the DC output voltage V1 from the power supply unit 51, for example, the power supply unit 51 is normally operated in the critical mode, and When it is detected that the DC output voltage V1 starts to increase due to the load becoming lighter with respect to the DC output voltage V1, such as when the lamp 12 is in a deep dimming state, the mode is switched to the current discontinuous mode.

  Note that the operation switching point included in the dimming signal DIM, or each threshold value of the input voltage V0 and the switching current ID may be fixed, or may be varied according to a predetermined signal or the like.

  Further, the chopping PWM signal PC may be variable in on-duty or variable in frequency.

  The preheating circuit control unit 72 is a software unit having a function of preheating current detection means for detecting the preheating current IP of the preheating circuit 55, and monitors the preheating current IP of the preheating circuit 55 while detecting the lamp detected by the state detection unit 73. The gate terminal of the field effect transistor Q4 of the preheating circuit 55 is set so that the optimum preheating condition, that is, the target value is set so as to follow the change of at least one of the current IL and the lamp voltage VL, and the preheating current IP approaches the target value. PWM signal PP for preheating to be supplied to is generated. Note that the preheating circuit control unit 72 may set the target value following a change in lamp power or a change in ambient temperature, which is the product of the lamp current IL and the lamp voltage VL, for example. The target value is preferably an upper limit set from an energy amount that does not cause a problem even at the end of the life of the filaments FLa and FLb.

  The state detection unit 73 is an A / D converter that is an arithmetic unit that converts at least one of the lamp current IL and the lamp voltage VL, which are analog signals, into digital frequency data corresponding to the lamp current IL and the lamp voltage VL. And outputs at least one of the A / D converted lamp current IL and lamp voltage VL to the preheating circuit control unit 72 or the dimming signal generation unit 74. The detection timing of the lamp current IL or the lamp voltage VL in this state detection unit 73 is, for example, at least one analog signal in the main circuit 59 such as a power supply voltage waveform or a voltage across the resonance capacitor C4, or The timing is synchronized with the peak phase of the lamp current IL or the lamp voltage VL based on predetermined frequency data which is a digital signal calculated based on the lamp current IL or the lamp voltage VL detected by the state detector 73. . In the present embodiment, for example, since the state detection unit 73 has a function of an A / D converter, it is based on predetermined frequency data that is a digital signal calculated based on the lamp current IL, the lamp voltage VL, and the like. Thus, the detection timing of the lamp current IL or the lamp voltage VL is determined.

  Then, the dimming signal generation unit 74 has a predetermined frequency based on the lighting state of the lamp 12 detected by the state detection unit 73, that is, at least one of the lamp current IL and the lamp voltage VL, and the dimming signal DIM. It has a function of a signal generation part which generates PWM signal P which has.

  The dimming signal detection unit 75 has a function of an A / D converter that converts the dimming signal DIM from the dimming signal unit 57 that is an analog signal into digital frequency data corresponding to the dimming signal DIM. Have.

  The ROM stores in advance various programs to be executed by each unit of the DSP 56, for example, the switching unit 71, the preheating circuit control unit 72, the dimming signal generation unit 74, and the like.

  In the RAM, various digital values detected by the state detection unit 73 and the like are stored in areas assigned to them.

  The dimming signal unit 57 is a signal output unit 81 for outputting a signal corresponding to the dimming signal DIM, and a full-wave rectification of the signal output from the signal output unit 81 to adjust the DSP 56 as a dimming signal DIM. And a full-wave rectifying element REC2 that outputs to the optical signal detector 75.

  Next, the operation of the above embodiment will be described.

  In the power supply unit 51, the lighting device 42 generates a chopping PWM signal PC by the switching unit 71 of the DSP 56 to switch the field effect transistor Q1, and adjusts the phase of the input voltage V0 and the input current I0 to increase the power factor. Improve. At this time, the switching unit 71 includes an operation switching point included in the dimming signal DIM output from the dimming signal unit 57, a switching current ID flowing through the input voltage V0 and the field effect transistor Q1, and a direct current from the power supply unit 51. The critical mode and the current discontinuous mode are switched according to at least one of the output voltage V1.

  Specifically, as shown in FIGS. 1 and 3, when the field effect transistor Q1 is turned on by a starting circuit (not shown) or the like, a linearly increasing current flows through the chopper choke L1 (diode D1). A choke current I flows through the secondary winding L1b of the chopper choke L1, and electromagnetic energy is accumulated in the chopper choke L1. When the detected switching current ID reaches a predetermined value, the switching unit 71 of the DSP 56 outputs an off chopping PWM signal PC to the gate terminal of the field effect transistor Q1 via the driver element 61 to turn off the field effect transistor Q1. To do. As a result, electromagnetic energy accumulated in the chopper choke L1 is released, and a linearly decreasing current flows through the chopper choke L1 (diode D1).

  When the power supply unit 51 is operated in the critical mode, the switching unit 71, when the detected choke current I becomes 0, immediately turns on the chopping PWM signal PC via the driver element 61 to the gate terminal of the field effect transistor Q1. 3 and repeating the above operation, the output current I1 becomes critically continuous with the reference waveform SW as an envelope, as shown in FIG. 3 (a).

  On the other hand, when operating the power supply unit 51 in the current discontinuous mode, the switching unit 71 sets the frequency, off width, and on timing of the chopping PWM signal PC of the field effect transistor Q1 even if the detected choke current I becomes zero. Are intentionally (forcedly) changed with respect to the output timing in the coastal mode and output via the driver element 61. As a result, as shown in FIG. 3B, the output current I1 becomes discontinuous with the reference waveform SW as an envelope.

  The DC output voltage V1 generated by the power supply unit 51 is converted into a high-frequency AC voltage by operating the field effect transistors Q2 and Q3 of the inverter circuit 52 at a predetermined frequency such as 50 kHz and a predetermined on-duty, for example. The

  By this high frequency AC voltage, the resonance circuit 53 resonates and a resonance current flows, and the field effect transistor Q4 is switched by the preheating PWM signal PP having a predetermined frequency generated by the preheating circuit control unit 72. A preheating current IP flows through the secondary windings L3b and L3c of the preheating transformer L3 to preheat the filaments FLa and FLb of the lamp 12.

  A predetermined starting voltage is applied between the filaments FLa and FLb by preheating the filaments FLa and FLb, the lamp 12 is turned on (started), and the lamp 12 is steadily lit.

  At this time, the lighting device 42 generates a dimming signal based on the dimming signal DIM input from the dimming signal unit 57, the lamp current IL detected by the state detection unit 73, or at least one of the lamp voltage VL. The unit 74 inputs the PWM signal P to the high-side driver 65 and varies the drive frequency of the inverter circuit 52, so that the lamp current IL, the lamp voltage VL, or the lamp power that is the product of these is the predetermined target value. Feedback control is performed as follows.

  In the preheating circuit 55, the preheating current is set to the target value set by the preheating circuit control unit 72 so as to follow the lamp current IL, the lamp voltage VL, the lamp power, or the ambient temperature change detected by the state detection unit 73. The field effect transistor Q4 is switched by the preheating PWM signal PP generated so that the IP approaches, thereby optimizing the amount of preheating during lighting that varies depending on the type of the lamp 12 and variations in the manufacturing process.

  As described above, the switching unit 71 changes the operation mode of the power supply unit 51 between the critical mode and the current according to predetermined signals such as the dimming signal DIM, the input voltage V0, the DC output voltage V1, the choke voltage V, and the switching current ID. By switching to the discontinuous mode, the power supply 51 is normally operated in the critical mode, and when the load is light, the power supply 51 can be switched to the current discontinuous mode to suppress the increase in the output DC voltage V1. By varying the on-duty of the chopping PWM signal PC with respect to the minimum on-width in the critical mode, deep dimming is possible.

  In addition, since the chopping PWM signal PC is not generated using a comparator or the like, the minimum on width of the chopping PWM signal PC is not determined by the response time of the comparator, and the output of the lamp 12 is less than an arbitrary output. It becomes possible to focus on.

In the above-described embodiment, the detailed configurations of the power supply unit 51, the inverter circuit 52, the resonance circuit 53, the preheating circuit 55, and the like are not limited to the above configuration and control .

It is a circuit diagram of a load control device showing an embodiment of the present invention. It is a bottom view which made a part of electric equipment provided with a load control device same as the above in the cross section. (a) is a graph showing the operation in the critical mode of the power factor improvement circuit of the load control device, (b) is a graph showing the operation in the current discontinuous mode of the power factor improvement circuit of the load control device.

11 Recessed ceiling lighting fixtures as electrical equipment
12 Lamp as load
42 Discharge lamp lighting device as load control device
51 Power supply as a power factor correction circuit
57 Dimming signal section
58 lighting circuit
71 Switching unit as switching means
DIM dimming signal
Q1Field effect transistor as the first switching element
Q2 and Q3 field effect transistors as second switching elements

Claims (2)

Comprising a first switching element, a power factor correction circuit for converting a DC voltage obtained by boosting the input voltage by the switching operation of the first switching element;
A dimming signal unit for inputting a dimming signal from the outside;
A second switching element is provided, and the DC voltage converted by the power factor correction circuit is converted and output by the switching operation of the second switching element to light the load, and to the dimming signal input to the dimming signal unit A lighting circuit to dimm the load accordingly ;
Switching means for controlling the switching operation of the first switching element and switching the operation mode of the power factor correction circuit between the critical mode and the current discontinuous mode according to at least the dimming signal ;
A load control device comprising: A load control device according to claim 1;
A load controlled by the load control device;
An electrical apparatus comprising:

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