JP2012100484A - Power supply unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power supply unit that can significantly reduce inrush current during startup than that of a conventional one to suppress voltage fluctuations of a DC voltage.SOLUTION: A switching operation control section 15 performing on-off control of a switching element in an AC/DC conversion section stops the on-off control of the switching element until an output voltage measurement value Vdc reaches a startup voltage, and performs a target voltage generation control that gradually raises a target output voltage value Vref to an output voltage set value using the number of steps obtained from a predetermined startup processing time divided by a predetermined update cycle time after the output voltage measurement value Vdc reached the startup voltage until it reaches the output voltage set value.

Description

  The present invention relates to a power supply apparatus in a power system of various devices such as home appliances and industrial devices.

In recent years, in order to solve the problem of harmonic current flowing into the power systems of various appliances such as home appliances and industrial equipment, the power source in the equipment uses the energy storage effect due to the operation of the inductor and switching element to increase the power factor. An AC / DC converter circuit (AC-DC converter) that boosts the output voltage while improving is used.
In the control in this AC-DC converter, the AC voltage value (input voltage measurement value Vin) is set to the voltage difference value (Ev) between the DC voltage value (output voltage measurement value Vdc) and its target value (target output voltage value Vref). According to the value obtained by multiplication, the switching element conduction ratio (the ratio of the time during which the switching element is in the conduction state in the switching period of the switching element is determined. The time ratio is DUTY) is improved. (PFC: Power Factor Correction).

  For example, as disclosed in Patent Document 1, such a power supply device detects an AC / DC conversion unit (PFC unit) including at least a switching element, an inductor, and a diode, which obtains a DC voltage from an AC power source, and a current value of the AC power source. An input current detector that detects the voltage value of the AC power supply, a DC voltage detector that detects a DC voltage value output from the AC / DC converter, a current detector, an input voltage detector, and a DC A switching operation control unit that performs power factor improvement based on each value obtained by the voltage detection unit and performs PFC control of the operation of the switching element so that the DC voltage value becomes a preset target value (patent) (Refer FIG. 1 of literature 1).

  PFC control is generally performed as follows. The operation control unit calculates a voltage difference value Ev between the output voltage measurement value Vdc and the target output voltage value Vref in the voltage control loop, and generates a voltage error signal VPI. Thereafter, the input current set value Iref is obtained by multiplying the voltage error signal VPI by a value obtained by normalizing the input voltage measurement value Vin. Next, the control unit calculates a current difference value Ei between the input current setting value Iref and the input current measurement value Iin in the current control loop, and generates a current error signal IPI.

  Then, by sequentially converting the conduction ratio (DUTY) of the switching element according to the signal level of the current error signal IPI, the waveform of the input voltage measurement value Vin and the input current measurement value Iin are similar, and the power factor becomes 1. In other words, control is performed so that the phase of the input voltage and the input current is in phase, and the DC voltage becomes a predetermined target output voltage value Vref.

  Here, a ripple component having a frequency twice the AC power supply frequency is superimposed on the DC voltage (output voltage measurement value Vdc) obtained by the DC voltage detection unit due to the characteristics of the AC / DC converter circuit. If the above control calculation is performed while the ripple component is included in the DC voltage, the influence of the ripple component appears in the voltage error signal VPI, and eventually the waveform of the input current (input current measured value Iin) is distorted. .

  In order to eliminate this ripple component, a value obtained through a low-pass filter with a slow response speed (cutoff frequency of about 1 Hz) is used as the DC voltage value when calculating the voltage difference value Ev in the voltage control loop. It is common. On the other hand, since the current error signal IPI of the current control loop sequentially controls the duty so that the input current (input current measurement value Iin) follows a sinusoidal shape, it is common to set the cutoff frequency higher. .

JP 2008-289228 A

  However, according to the above-described configuration, when the power supply device is connected to, for example, a 200V commercial AC power supply and an input AC voltage is supplied, the DC voltage is the target output voltage value Vref (for example, 400V) when the PFC is activated. However, since the response of the voltage control loop is slow, the voltage difference (voltage difference value Ev) from the target output voltage value Vref is large, such as when the target output voltage value Vref is set to a constant value in advance. Due to the characteristic that the circuit performs a boost operation, the current error signal IPI of the current control loop rapidly increases. As a result, during the period until it rises to the target output voltage value Vref, it operates in a state where the conduction ratio (DUTY) of the switching element is widened (a state in which the switching element is on for a long period), and the inrush current at the start of PFC is The DC voltage increases and exceeds the target output voltage value Vref. On the other hand, since the voltage control loop reduces the response speed as described above, there is a problem that it takes time until the DC voltage returns to the target output voltage value Vref, and the responsiveness of the power supply device is poor.

  (1) In order to solve the above-mentioned problem, the present invention is a power supply device having a power factor improvement function, and is an AC / DC converter comprising at least a switching element, an inductor and a diode for obtaining a DC voltage from an AC voltage of an AC power supply. A current value of the AC power source, an input current detection unit that detects the voltage value of the AC power source, and a DC voltage that detects the voltage value of the DC voltage output by the AC / DC converter Based on the voltage detection unit, the input current detection unit, the input voltage detection unit and the DC voltage detection unit, the AC power supply current value, the AC power supply voltage value and the DC voltage value, respectively. A switching operation control unit that controls on / off of the switching element so that a voltage value of a DC voltage becomes a preset output voltage setting value; A target output voltage calculation unit that generates a target output voltage value that is an upper limit value of on / off control of the voltage value of the DC voltage, and until the voltage value of the DC voltage reaches the output voltage setting value, A target voltage for stepwise increasing the target output voltage value to the output voltage set value by the number of steps obtained by dividing the preset start processing time for turning on / off the switching element by a preset update cycle time. A power supply device having a target output voltage calculation unit, characterized by performing generation control.

  (2) Further, according to the present invention, the target output voltage calculation unit includes an output voltage measurement value Vdc input from the DC voltage detection unit, and a start start voltage value Vstart in the previous target output voltage value Vref generation processing flow. And processing to obtain a new start voltage value Vstart is performed.

  (3) Further, in the present invention, the AC / DC conversion unit includes a relay circuit between the AC voltage input terminal and the switching operation control unit before the relay circuit is turned on. A voltage value of the DC voltage is set as the start voltage value, and after the relay circuit is turned on, the voltage of the DC voltage is updated every cycle after the cycle of the AC voltage is multiplied by a preset number of cycles. The output voltage setting value and the start start voltage value after the elapse of a period obtained by multiplying the average of the start value and the start start voltage value as the new start start voltage value and multiplying the cycle of the AC voltage by a preset number of cycles Is divided by the number of steps to calculate a voltage increase per step, and the target output voltage value is increased stepwise by the voltage increase.

  (4) In the present invention, the switching operation control unit compares the target output voltage value with the target output voltage calculation unit that generates the target output voltage value, the value obtained by normalizing the output voltage measurement value, and the target output voltage value. Taking the difference, generating a voltage difference value, multiplying the voltage difference value and the voltage gain, generating a voltage error signal, a value obtained by normalizing the input voltage measurement value, A multiplier that multiplies the voltage error signal to generate the input current set value, and compares the input current set value with a value obtained by normalizing the input current measurement value, and generates a current difference value by taking the difference between them. A current error signal generation unit that generates a current error signal by multiplying the current difference value and the current gain, and a pulse width for turning on the switching element based on the current error signal, for example, a current Ratio D from error signal IPI Calculated by using an arithmetic expression for converting the TY, characterized in that and a ratio calculation unit when outputting to the switching operation control unit.

  (5) Further, according to the present invention, the switching operation control unit may calculate the duty ratio DUTY by using the current error signal IPI obtained in the PID calculation process in the duty ratio calculation unit, DUTY = Dmax−IPI × Kcnv (Dmax is It is a maximum output value (upper limit value) of the time ratio DUTY, and Kcnv is a coefficient for converting the current error signal IPI into the time ratio DUTY.

  (6) Further, according to the present invention, the PID calculation process in the duty ratio calculation unit calculates the current difference value Ei (t) by Ei (t) = input current set value Iref−input current measurement value Iin (t). Then, the current error signal IPI = Ui (t) obtained by the PID calculation process is expressed as Ui (t) = Kip × Ei (t) + {Kii × Ei (t−1) + Ui (t−1)} + Kid × {Ei (T) −Ei (t−n)} (Ui (t−1) is the current error signal IPI obtained in the previous PID calculation process, and Ei (t−1) and Ei (t−n) are The current difference value Ei in the PID calculation process one time before and n times before is shown, Ei (t) is a value according to the result of this process, and Kip, Kii, and Kid are respectively PID calculation processes. (Proportional (P) coefficient, integral (I) coefficient, differential (D) coefficient are shown.) Characterized by further operations.

  (7) Further, according to the present invention, the switching operation control unit includes an offset calculation unit that generates an offset value used for the offset subtraction process in the duty ratio calculation unit. In the offset calculation unit, the offset determination threshold THoffset and the voltage Based on the difference from the error signal VPI, the offset value Offset is set to Offset = (THoffset−VPI) × Koffset (Koffset is a coefficient value calculated in advance by experiment or simulation, and is a value set in the switching operation control unit. The calculation is performed by the following.

  (8) Further, according to the present invention, in the duty ratio calculation unit, the duty ratio DUTY is calculated based on the offset value Offset, and DUTY (t) = DUTY (t−1) −Offset (DUTY (t) is subtracted this time. It is a time ratio DUTY obtained by processing, and DUTY (t−1) is a time ratio DUTY obtained by the previous subtraction process).

  According to the present invention, at the time of start-up by a commercial power source, a preset start-up processing time (start-up processing time Tsoftstart) is set in advance until the output voltage reaches the output voltage set value (output voltage set value Vset). The target voltage generation control is performed in which the target output voltage value (target output voltage value Vref) is stepped up to the output voltage set value by the number of steps divided by the update cycle time.

  Accordingly, the voltage difference (voltage difference value Ev) between the DC voltage value (output voltage measurement value Vdc) and the target output voltage value Vref can be reduced at the time of startup, so that the error signal (IPI) of the current control loop increases rapidly. The switching operation can be performed in a state where the duty is narrowed (the switching element is turned on for a short period), and the inrush current at the start-up can be greatly suppressed as compared with the conventional power supply device. Responsiveness can be improved.

  The AC / DC conversion unit includes a relay circuit between the input terminal to which an AC voltage is input, and the switching operation control unit sets a cycle number set in advance to the cycle of the AC voltage after turning on the relay circuit. After the multiplied period has elapsed, target voltage generation control is performed. In addition, the switching operation control unit sets the DC voltage before turning on the relay circuit as a predetermined start-up start voltage value, and calculates an average of the DC voltage and the predetermined voltage value for each update cycle in a period multiplied by the number of cycles. It is set as a new predetermined voltage value. Thereby, since the voltage difference can be shifted to the soft start period in a smaller state, the inrush current can be further suppressed, and the voltage fluctuation of the output voltage measurement value can be suppressed.

It is a circuit block diagram which shows the power supply device in embodiment of this invention. It is a circuit block diagram of the switching operation control part 15 shown in FIG. It is an operation | movement waveform diagram at the time of starting of the power supply device shown in FIG. It is a flowchart which shows the target output voltage value Vref production | generation process of the switching operation control part 15 at the time of starting. It is a flowchart which shows the duty ratio DUTY update control of the switching operation control part 15. It is an operation | movement waveform diagram of the power supply device shown in FIG.

Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings.
FIG. 1 is a circuit configuration diagram showing a power supply device according to an embodiment of the present invention.
The power supply device shown in FIG. 1 converts the AC voltage of the first and second AC input terminals 1a and 1b connected to a commercial AC power supply (AC power supply) into a DC voltage, and first and second DC output terminals. This is a power supply device that generates a DC voltage between 2a and 2b and supplies the DC voltage to a DC-DC converter or the like connected between these output terminals.

  The power supply apparatus includes an input stage filter circuit FLTR, a relay circuit RY, and a power factor improvement between the first and second AC input terminals 1a and 1b and the first and second DC output terminals 2a and 2b. A circuit PFC is provided in order. The power supply apparatus further includes an input voltage detection unit 11 and an input current detection unit 12 for on / off control of switching elements (transistors Q1 and Q2, diodes BD1 and BD2) included in the power factor correction circuit PFC. And an SW drive unit 13, an output voltage detection unit 14, and a switching operation control unit 15.

  In the power factor correction circuit PFC of FIG. 1, a diode D1, a transistor Q1, and a resistor R1 are connected in series between the DC output terminal 2a and the DC output terminal 2b. A diode D2, a transistor Q2, and a resistor R2 are connected in series between the DC output terminals 2a and 2b. A diode BD1 and a diode BD2 are connected in parallel to the transistor Q1 and the transistor Q2, respectively, and these two parallel circuits function as switching elements of the power factor correction circuit PFC.

  The connection point between the diode D1 and the transistor Q1 is connected to the AC input terminal 1a side via the inductor L1, and the connection point between the diode D2 and the transistor Q2 is connected to the AC input terminal 1b side via the inductor L2. Connected to. An electrolytic capacitor C2 is also connected between the DC output terminals 2a and 2b. The transistors Q1 and Q2 are N-channel MOS transistors in FIG. 1, but in this case, the diodes BD1 and BD2 may be parasitic diodes in the MOS transistors. Further, an NPN bipolar transistor or IGBT may be used as the transistors Q1 and Q2.

  When the transistor Q1 is on during the positive voltage period of the AC power supply connected to the AC input terminals 1a and 1b, the first closed circuit comprising the AC input terminal 1a, the inductor L1, the transistor Q1, the diode BD2, and the inductor L2 A circuit is formed and stores energy in inductor L1. Next, when the transistor Q1 is turned off, the second closed circuit including the AC input terminal 1a, the inductor L1, the diode D1, the electrolytic capacitor C2, the diode BD2, and the inductor L2 transfers the energy stored in the inductor L1 to the electrolytic capacitor C2. Then, the electrolytic capacitor C2 is charged as a DC voltage to a value higher than the AC power supply voltage.

On the other hand, in the negative voltage period of the AC power supply, when the transistor Q2 is on, a third closed circuit including the AC input terminal 1b, the inductor L2, the transistor Q2, the diode BD1, and the inductor L1 is formed, and the inductor L2 To store energy. Next, when the transistor Q2 is turned off, the fourth closed circuit including the AC input terminal 1b, the inductor L2, the diode D2, the electrolytic capacitor C2, the diode BD1, and the inductor L1 transfers the energy stored in the inductor L2 to the electrolytic capacitor C2. And the electrolytic capacitor C2 is charged to a value higher than the AC power supply voltage.
In the positive voltage period or negative voltage period of the AC power supply, only one of the transistors Q1 and Q2 is required to be turned on / off as described above, but the two transistors are connected using the same gate signal. It may be turned on / off.

  With such a configuration, the power factor correction circuit PFC turns on / off the switching element and controls the voltage between both terminals of the electrolytic capacitor C2 to be constant, but the AC power supply connected to the AC input terminals 1a, 1b It is necessary to perform on / off control of the switching element at a frequency higher than the voltage frequency. Therefore, the switching operation control unit 15 performs an arithmetic operation for determining the conduction ratio of the switching element (the ratio of the time during which the switching element is in the conduction state in the switching cycle of the switching element. Hereinafter, the duty ratio is DUTY). This is based on the input voltage, AC input current, and DC output voltage.

  Therefore, in the power factor correction circuit PFC, both ends of each of the resistors R1 and R2 are connected to the input current detection unit 12, and the gate terminal and the source terminal of each of the transistors Q1 and Q2 are connected to the SW drive unit 13. The DC output terminals 2a and 2b are connected to the output voltage detection unit 14. In addition, the AC input terminals 1 a and 1 b side of the inductors L 1 and L 2 are connected to the input voltage detection unit 11.

  The input voltage detection unit 11 detects an AC voltage and outputs an input voltage measurement value Vin (voltage value of the AC power supply) to the switching operation control unit 15. Further, the input current detection unit 12 detects an alternating current flowing through the resistors R1 and R2, and outputs an input current measurement value Iin to the switching operation control unit 15. The output voltage detection unit 14 (DC voltage detection unit) detects the voltage between the DC output terminals 2 a and 2 b and outputs the output voltage measurement value Vdc to the switching operation control unit 15.

  The switching operation control unit 15 generates a duty ratio DUTY based on the voltage levels of these input signals and outputs the duty ratio DUTY to the SW drive unit 13. The SW drive unit 13 generates a drive signal for the switching element based on the duty ratio DUTY.

  Further, the switching operation control unit 15 turns on the switch of the relay circuit RY. For this reason, the input voltage measurement value Vin is monitored, and the AC power source is peak-charged with the electrolytic capacitor C2. The time when the AC power source effective value x√2 is reached and the effective value of the AC power source can be recognized is reached. After the elapse of time, the relay circuit RY is turned on to lower the impedance with respect to the AC input terminal of the power factor correction circuit PFC. The resistor (resistor R3) in the relay circuit RY forms a CR time constant circuit together with the capacitor capacity provided before and after the relay circuit RY, and the electrolytic capacitor C2 of the power factor improving circuit PFC before the switching operation is started. This prevents a sudden current from flowing.

FIG. 2 is a circuit configuration diagram of the switching operation control unit 15.
The switching operation control unit 15 includes a target output voltage calculation unit 20, a voltage error signal generation unit 21, a current error signal generation unit 22, a time ratio calculation unit 23, normalization calculation units 31 to 33, comparators 41 and 43, and a multiplier. 42.

  The target output voltage calculation unit 20 is a circuit that generates a target output voltage value Vref, and forms a characteristic part of the present invention. Details will be described later with reference to waveform diagrams and operation flows.

  The voltage error signal generation unit 21 includes a comparator 41 and a VPI generation unit 26, and generates a voltage error signal VPI. The comparator 41 is a value obtained by normalizing the output voltage measurement value Vdc by the normalization calculation unit 31 (the output voltage measurement value Vdc is multiplied by a coefficient k1, for example, 1/100 so as to match the operation voltage of the switching operation control unit 15. And the target output voltage value Vref and take the difference to generate the voltage difference value Ev. The VPI generator 26 multiplies the voltage difference value Ev and the voltage gain Gv to generate a voltage error signal VPI. Here, as is well known in the feedback control system, calculation processing of proportional P, integral I, and differential D, which is called PID, is added to the voltage error, and these are synthesized and fed back as necessary, and the response of the system It is done to improve sex. The voltage gain Gv is a value obtained by this PID calculation process.

  The multiplier 42 is a value obtained by normalizing the input voltage measurement value Vin by the normalization calculation unit 32 (for example, a value obtained by dividing the input voltage measurement value Vin by the maximum value k2 so as to match the operation voltage of the switching operation control unit 15. ) And the voltage error signal VPI to generate an input current set value Iref.

  Further, the comparator 43 is a value obtained by normalizing the input current measurement value Iin by the normalization calculation unit 33 (a value obtained by multiplying the input current measurement value Iin by a coefficient k3 so as to match the operation voltage of the switching operation control unit 15). Is compared with the input current set value Iref, and the difference is taken to generate the current difference value Ei. The IPI generator 27 multiplies the current difference value Ei and the current gain Gi to generate a current error signal IPI. The current gain Gi is a value obtained by the PID calculation process, similarly to the voltage gain Gv.

  Based on the current error signal IPI, the time ratio calculator 23 calculates a pulse width (duty ratio DUTY) for turning on the switching element, for example, using an arithmetic expression for converting the current error signal IPI to the duty ratio DUTY. And output to the SW drive unit 13. The SW drive unit 13 determines whether or not to perform the switching operation at the input duty ratio DUTY based on a control operation command or the like, outputs a drive signal, and turns on / off the switching element. By executing this switching operation, the waveform of the input voltage measurement value Vin and the input current measurement value Iin is similar, and the power factor becomes 1, that is, the input voltage measurement value Vin and the input current measurement value Iin. Control is performed so that the phase is in phase and the DC voltage becomes a predetermined target output voltage value Vref.

  In the above circuit configuration, when the voltage difference (voltage difference value Ev) increases, the current or voltage level of the error signal (IPI) increases and the duty is increased (the switching element is turned on for a long period). When the switching operation is performed and the voltage difference (voltage difference value Ev) decreases, the current or voltage level of the error signal (IPI) decreases, and the logic that performs the switching operation in a state where the duty is narrowed (a state in which the switching element is turned on is short). It has a configuration.

Next, the target output voltage value Vref generation process of the switching operation control unit 15 at the time of startup will be described with reference to FIGS. 3 and 4.
FIG. 3 is an operation waveform diagram at the time of startup of the power supply apparatus, and FIG. 4 is a flowchart showing target output voltage value Vref generation processing of the switching operation control unit 15 at the time of startup.
In the following description, it is assumed that the power supply device is connected to an AC power source having an effective value, for example, 200 V (P-P between peak values is 283 V), as shown in FIG. To do.

  In FIG. 3, “link voltage” indicates an output voltage measurement value Vdc that is an output of the power supply apparatus, and “auxiliary power supply (+5 V)” indicates a power supply voltage supplied to the switching operation control unit 15. Since the switching operation control unit 15 is configured by, for example, a microcomputer (MCU), an operation voltage of 5 V is supplied. The “PFC microcomputer state” is, in order from “stopped state”, “CPU initialization” state after turning on auxiliary power, “input determination” state, “link voltage stabilization wait” state, “stability wait after relay ON” State, “soft start” state, “normal operation” state. Also, the time or cycle shown above each state indicates the time required for each state of the microcomputer.

  The auxiliary power is turned on at time t1, and the switching operation control unit 15 initializes the internal circuit between times t1 and t2. After that, the switching operation control unit 15 determines the effective value of the AC power source based on the input voltage measurement value Vin input to the input voltage detection unit 11 in several cycles of the commercial AC input period between times t2 and t3. Do.

  When it is determined at time t3 that the effective value of the AC power source is recognizable, the switching operation control unit 15 shifts to the “link voltage stabilization wait” state. This is a state where the switching operation is stopped until time t4. However, the switching operation control unit 15 causes the voltage value to rise to the effective value of the AC power source × √2 by the output voltage measurement value Vdc input to the output voltage detection unit 14 (DC voltage detection unit). Is monitoring. Further, the target output voltage calculation unit 20 generates the start start voltage value Vstart for each update cycle (update cycle time) after time t3. Details will be described later with reference to FIG.

  Next, at time t4, the switching operation control unit 15 shifts to the “waiting for stability after relay ON” state, turns on the relay circuit RY, and reduces the impedance between the AC power supply and the power supply device. In the figure, the period from t3 to t4 is a period of 3 cycles of the commercial AC input period, but this value is an example and may be 3 cycles or more.

  Next, at time t5, the switching operation control unit 15 shifts to a “soft start” state and starts a switching operation. Further, after time t5, the target output voltage calculation unit 20 updates the target output voltage value Vref for each update cycle after the switching operation is started, and gradually increases it to the output voltage set value Vset. Details will be described later with reference to FIG.

  Next, when the target output voltage value Vref coincides with the output voltage set value Vset at time t6, the target output voltage calculation unit 20 stops updating the target output voltage value Vref and puts the power supply device in the “normal operation” state. Transition.

Next, the target output voltage value Vref generation process of the target output voltage calculation unit 20 will be described with reference to FIG.
When the target output voltage calculation unit 20 determines that the effective value of the AC power supply can be recognized, the target output voltage calculation unit 20 shifts to the “link voltage stabilization wait” state shown in FIG. 3 (time t3). After this time is the target output voltage value Vref generation processing time in the present invention, which is periodically executed for each update cycle. The switching operation control unit 15 includes a timer in which a time corresponding to the times t3 to t6 is set. When the switching operation control unit 15 shifts to the “waiting for link voltage stabilization” state at the time t3, the timer is activated until the time t6. In this period, the timer is referred to every update cycle to determine whether or not it is in the period from time t3 to t6 (referred to as “target voltage generation control period”), and the elapsed time from time t3 is acquired. In addition, a period (time t5 to t6) in which the target output voltage value Vref is increased stepwise is set as a startup processing time Tsoftstart.

  The target output voltage calculation unit 20 refers to the internal timer and determines whether or not it is in the target voltage generation control period (step S1). If it is determined that it is not within the target voltage generation control period, this process ends (step S1-No), and after the update cycle has elapsed, the process returns to step S1. On the other hand, when it determines with it being in the target voltage generation control period, it progresses to step S2 (step S1-Yes).

  In step S2, whether or not the PFC operation mode (switching mode is performed) is determined, for example, based on whether or not the target output voltage value Vref is output (whether the target output voltage value Vref> 0V) ( Step S2). When it determines with it being in PFC operation mode, it progresses to step S8 (step S2-Yes), and when it determines with it not being in PFC operation mode, it progresses to step S3 (step S2-No).

  Step S3 and subsequent steps are a starting start voltage value Vstart determination processing flow, which corresponds to the processing at time t3 to t5 in FIG. In the activation start voltage value Vstart determination processing flow, since the switching operation has not yet started, the target output voltage value Vref is set to 0 V (step S3), and the activation elapsed time Tpass is set to 0 ms (step S4).

  Next, in step S5, the switching operation control unit 15 determines whether or not the relay circuit RY is connected based on the voltage level of the switch signal of the relay circuit RY. If it is determined that the relay circuit RY is connected, the process proceeds to step S7 ( If it is determined that the connection is not being established (step S5-Yes), the process proceeds to step S6 (step S5-No).

  In step S6, the startup start voltage value Vstart is initialized. That is, the switching operation control unit 15 sets the output voltage measurement value Vdc input from the output voltage detection unit 14 as the start start voltage value Vstart. The period in which this process is performed corresponds to the time t3 to t4 in FIG. 3, and is a period in which the output voltage measurement value Vdc gradually increases.

  In step S7, the start start voltage value Vstart is updated. That is, the switching operation control unit 15 takes an average value of the output voltage measurement value Vdc input from the output voltage detection unit 14 and the start target voltage value Vstart in the previous target output voltage value Vref generation processing flow, and The start-up voltage value is Vstart. That is, the process shown by the following formula (1) is performed.

Startup start voltage value Vstart (t) = (Startup start voltage value Vstart (t-update cycle) + Output voltage measured value Vdc (t-update cycle)) / 2 (1)
The period in which this process is performed corresponds to the time t4 to t5 in FIG. 3, and is a period in which the relay circuit RY is turned on and the voltage level of the output voltage measurement value Vdc is waiting to be stabilized.

  If it is determined in step S2 that the operation mode is the PFC operation mode, the target output voltage calculation unit 20 proceeds to step S8 and performs setting processing of the target output voltage value Vref. In step S8, for example, it is determined whether or not the activation process is being performed (switching operation is in progress) based on the value of the activation elapsed time Tpass. When the value of the start elapsed time Tpass is shorter than the start processing time Tsoftstart, it is determined that the start processing is in progress. When the start elapsed time Tpass is equal to or greater than the start processing time Tsoftstart, it is determined that the start processing is not in progress.

  Alternatively, the determination may be made by comparing the target output voltage value Vref and the output voltage set value Vset. When the target output voltage value Vref is less than 400V, it is determined that the activation process is being performed. When the target output voltage value Vref is 400V, it is determined that the activation process is not being performed. In any method, when it is determined that the target output voltage calculation unit 20 is being activated, the process proceeds to step S9 (step S8-Yes), and when it is determined that the activation process is not being performed, the process proceeds to step S11 (step S11). S8-No).

In step S9, the startup elapsed time Tpass is set. The target output voltage calculation unit 20 refers to the internal timer and increases the startup elapsed time Tpass by the update cycle.
In subsequent step S <b> 10, the target output voltage calculation unit 20 in the switching operation control unit 15 performs update setting of the target output voltage value according to the following equation (2), and outputs the target output voltage value Vref to the comparator 41. .

Target output voltage value Vref = (output voltage setting value Vset−starting start voltage value Vstart) × starting elapsed time Tpass / starting processing time Tsoftstart + starting start voltage value Vstart (2)
Note that the activation start voltage value Vstart in Equation (2) is a value when the activation elapsed time Tpass = 0 ms.

  If it is determined in step S8 that the activation process is not being performed, the switching operation control unit 15 proceeds to step S11, and sets the target output voltage value Vref as the output voltage setting value Vset. In normal operation after time t6 in FIG. 6, the power supply device operates under this set condition.

  As described above, according to the present invention, when the DC voltage (output voltage measurement value Vdc) reaches a predetermined start start voltage value (start start voltage value Vstart) at the time of start-up by a commercial power source, Stop on / off control. After the DC voltage (output voltage measurement value Vdc) reaches the start start voltage value (start start voltage value Vstart), the output voltage is set in advance until the output voltage reaches the output voltage set value (output voltage set value Vset). The target output voltage value (target output voltage value Vref) to the output voltage set value (output voltage set value Vset) by the number of steps obtained by dividing the startup process time (startup process time Tsoftstart) by a preset update cycle time. The target voltage generation control for increasing in steps is performed.

  Therefore, since the voltage difference (voltage difference value Ev) between the DC voltage (output voltage measurement value Vdc) and the target output voltage value Vref can be reduced at startup, the error signal (IPI) of the current control loop increases rapidly. In other words, the switching operation can be performed in a state where the duty is narrowed (a state in which the switching element is turned on is short).

  Thereby, as shown in the waveform of the link voltage in FIG. 3, the voltage waveform of the output voltage measurement value Vdc changes abruptly as in the past, and the voltage waveform VC that exceeds the output voltage set value Vset A voltage waveform VN that changes almost linearly with respect to the output voltage set value Vset from the start start voltage value Vstart (startup elapsed time Tpass = 0 ms) can be obtained. That is, the inrush current at the time of start-up can be greatly suppressed as compared with the conventional case, and the voltage fluctuation of the output voltage measurement value Vdc can be suppressed.

  The AC / DC converter is provided with a relay circuit RY between the input terminal to which an AC voltage is input, and the switching operation control unit 15 is set in advance to the cycle of the AC voltage after turning on the relay circuit RY. The target voltage generation control is performed after the elapse of the period multiplied by the number of cycles (after time t5 in FIG. 3). Further, the switching operation control unit 15 sets the DC voltage (output voltage measurement value Vdc at time t4 in FIG. 3) before turning on the relay circuit RY as a predetermined start start voltage value (start start voltage value Vstart), and the number of cycles. In the period multiplied by (period from time t4 to t5 in FIG. 3), the average of the DC voltage (output voltage measurement value Vdc) and the predetermined voltage value (Vstart) is updated to a new predetermined voltage value (Vstart) for each update cycle. (Step S7).

  As a result, the voltage difference (voltage difference value Ev) can be shifted to the soft start period (the period from time t5 to time t6 in FIG. 3) in a state where the voltage difference is further reduced. It is possible to suppress the voltage fluctuation of the output voltage measurement value Vdc.

Subsequently, the duty ratio DUTY update control (PWM output control) of the switching operation control unit 15 will be described with reference to FIGS. 5 and 6.
FIG. 5 is a flowchart showing duty ratio update control (PWM output control) of the switching operation control unit 15, and FIG. 6 is an operation waveform diagram of the power supply apparatus.
In the following description, the power supply device is assumed to be connected to, for example, an AC power supply having a frequency of 50 Hz. In FIG. 6, the input voltage measurement value Vin, voltage error signal VPI, current error signal IPI, and time ratio for one frequency are shown. A change in the voltage (Vgs) between DUTY and the gates and sources of the transistors Q1 and Q2 is shown.

The switching operation control unit 15 executes a duty ratio DUTY update control (PWM output control) for each update cycle. First, the switching operation control unit 15 acquires the input voltage measurement value Vin from the input voltage detection unit 11 (step S21), and performs the calculation process of the input current set value Iref in the voltage control loop (step S22). As for the calculation, the multiplier 42 matches the voltage error signal VPI according to the following equation (11), and the normalization calculation unit 32 normalizes the input voltage measurement value Vin (to match the operating voltage of the switching operation control unit 15). And the value divided by the maximum value k2 of the input voltage measurement value Vin).
Iref = VPI × NVin (11)

Next, the switching operation control unit 15 acquires the input current measurement value Iin from the input current detection unit 12 (step S23), and performs a calculation process of the current error signal IPI in the current control loop (step S24). The calculation is performed by the current error signal generation unit 22 based on the input current setting value Iref and the acquired input current measurement value Iin (t) by the PID calculation represented by the following equations (12) to (14).
Current difference value Ei (t) = input current setting value Iref−input current measurement value Iin (t) (12)
Ui (t) = Kip × Ei (t) + {Kii × Ei (t−1) + Ui (t−1)} + Kid × {Ei (t) −Ei (t−n)} (13)
IPI = Ui (t) (14)
Here, Ui (t) is the current error signal IPI obtained by the current PID calculation process, and Ui (t−1) is the current error signal IPI obtained by the previous PID calculation process. Ei (t−1) and Ei (t−n) indicate current difference values Ei in the PID calculation process one time before and n times before, respectively, and Ei (t) is a value based on the current processing result. is there. Kip, Kii, and Kid represent a proportional (P) coefficient, an integral (I) coefficient, and a differential (D) coefficient, respectively, in the PID calculation process.

Next, the switching operation control unit 15 calculates the time ratio DUTY in the time ratio calculation unit 23 according to the following equation (15) based on the current error signal IPI obtained by the PID calculation process.
DUTY = Dmax−IPI × Kcnv (15)
Here, Dmax is the maximum output value (upper limit value) of the duty ratio DUTY, and is a value set in advance in the switching operation control unit 15 together with the minimum output value Dmin (lower limit value). Kcnv is a coefficient for converting the current error signal IPI into the duty ratio DUTY, is a coefficient value calculated in advance by experiment or simulation, and is also a value set in the switching operation control unit 15. .

  Subsequently, the switching operation control unit 15 determines whether or not the value calculated by the previously calculated voltage error signal VPI is greater than a preset threshold value (pulse width control threshold value, hereinafter referred to as an offset determination threshold value THoffset). (Step S26). If it is determined that the voltage error signal VPI is smaller than the offset determination threshold THoffset, the process proceeds to step S27 (step S26-Yes), and if it is determined to be large, the process proceeds to step S29 (step S26-No).

In addition, the switching operation control unit 15 calculates the offset value Offset by the following equation (16) based on the difference between the offset determination threshold value THoffset and the voltage error signal VPI in the offset calculation unit 30 (step S27).
Offset = (THoffset−VPI) × Koffset (16)
Here, Koffset is a coefficient value calculated in advance by experiment or simulation, and is a value set in the switching operation control unit 15.

Next, the switching operation control unit 15 calculates (subtracts) the time ratio DUTY in accordance with the following equation (17) using the offset value Offset obtained in step S27 in the time ratio calculation unit 23 (step S28).
DUTY (t) = DUTY (t−1) −Offset (17)
Here, DUTY (t) is the duty ratio DUTY obtained in the current subtraction process, and DUTY (t−1) is the duty ratio DUTY calculated in step S25 of the previous duty ratio DUTY update control (PWM output control). It is. In this subtraction process, DUTY (t) is calculated so as to be between the maximum output value Dmax (upper limit value) and the minimum output value Dmin (lower limit value).

  The switching operation control unit 15 sets the duty ratio DUTY (t) calculated in step S28 in the duty ratio calculation unit 23 as the duty ratio DUTY in the update cycle (step S29), and outputs it to the SW drive unit 13. If it is determined in step S26 that VPI is greater than THoffset (step S26-No), the time ratio DUTY, which is the previous processing result, becomes the time ratio DUTY in this update cycle as it is.

  The SW drive unit 13 determines whether or not to perform the switching operation at the input duty ratio DUTY based on a control operation command or the like, outputs a drive signal, and has a pulse width gate corresponding to the duty ratio DUTY. A signal is output to turn on / off the switching elements (transistors Q1, Q2). By executing this switching operation, the waveform of the input voltage measurement value Vin and the input current measurement value Iin is similar, and the power factor becomes 1, that is, the input voltage measurement value Vin and the input current measurement value Iin. Control is performed so that the phase is in phase and the DC voltage becomes a predetermined target output voltage value Vref.

  Summarizing the above operations, when the voltage error signal VPI becomes lower than the preset offset determination threshold value THoffset, the switching operation control unit 15 determines the offset value Offset based on the difference between the offset determination threshold value THoffset and the voltage error signal VPI. Is calculated. Also, the duty ratio calculation unit 23 performs a minus offset calculation process represented by the above equation (17) on the duty ratio DUTY based on the offset value Offset, and determines to narrow the duty ratio DUTY.

  That is, according to the present embodiment, as shown in FIG. 6, in the current control loop, the waveform of the current error signal IPI is substantially the same as that of the conventional waveform IC shown in FIG. The waveform IN shown in FIG. Therefore, as shown in FIG. 6B, when the voltage error signal VPI becomes lower than the offset determination threshold value THoffset, it is possible to perform control to narrow the duty ratio DUTY as compared with the conventional case (FIG. 6A). Then, the SW drive unit to which the duty ratio DUTY is input outputs a pulse (indicated by Vgs in the drawing) that shortens or does not turn on the switching element.

  As described above, according to the present invention, the voltage error amplification signal (VPI) is not monitored in the voltage control loop with a slow response speed, but the voltage error amplification signal (VPI) is monitored, and the switching is performed in the current control loop with a fast response speed. An update operation for narrowing the conduction ratio (duty ratio) of the element is performed. Thereby, every time the switching element is turned on / off (in this case, the conduction ratio of the switching element can be controlled corresponding to each switching cycle, and the output voltage can be controlled almost uniformly even in a light load operation. Responsive to voltage fluctuations of a load that supplies DC voltage.

  According to the present invention, even in a sudden load change from normal operation, the current control loop works when the voltage error signal VPI becomes equal to or lower than the offset determination threshold value THoffset level, and every time the switching element is turned on / off (every switching frequency). Update. In addition, when the load suddenly changes from light load to rated load, the negative offset calculation is ignored at the moment when the offset determination threshold value becomes less than the THoffset level (step S26-No in the above flow). There is no influence by incorporation, and in this case as well, it can respond to changes in load with good response.

  Further, when the AC voltage input power source is activated, the above-described calculation control is started from a state where the voltage error signal VPI is almost zero. The switching operation is performed in a state in which is narrowed. Therefore, in the prior art, since the voltage difference value Ev is large, the switching operation is performed in a state where the duty ratio DUTY is widened, and the inrush current is increased. However, according to the present invention, the inrush current is increased by the soft start operation. There is also an effect of suppressing.

  The embodiment of the present invention has been described in detail with reference to the drawings. However, the specific configuration is not limited to this embodiment, and includes changes and the like without departing from the gist of the present invention.

  DESCRIPTION OF SYMBOLS 1a, 1b ... AC input terminal, 2a, 2b ... DC output terminal, FLTR ... Filter circuit, RY ... Relay circuit, PFC ... Power factor correction circuit, L1, L2 ... Inductor, D1, D2 ... Diode, Q1, Q2 ... Transistor , BD1, BD2 ... diode, R1, R2, R3 ... resistor, C2 ... electrolytic capacitor, 11 ... input voltage detection unit, 12 ... input current detection unit, 13 ... SW drive unit, 14 ... output voltage detection unit, 15 ... switching Operation control unit, Vdc ... output voltage measurement value, Iin ... input current measurement value, Vin ... input voltage measurement value, 20 ... target output voltage calculation unit, 21 ... voltage error signal generation unit, 22 ... current error signal generation unit, 23 ... Time ratio calculation unit, 26 ... VPI generation unit, 27 ... IPI generation unit, 30 ... Offset calculation unit, 31, 32, 33 ... Normalization calculation unit, 41, 43 ... Comparator 42 ... multiplier, Vref ... target output voltage value, Ev ... voltage difference value, Gv ... voltage gain, VPI ... voltage error signal, Iref ... input current set value, Ei ... current difference value, Gi ... current gain, IPI ... current Error signal, DUTY ... duty ratio, Vstart ... starting start voltage value, Vset ... output voltage setting value, Tsoftstart ... startup processing time, Tpass ... startup elapsed time

Claims (8)

A power supply device with a power factor correction function,
An AC / DC converter comprising at least a switching element, an inductor and a diode for obtaining a DC voltage from the AC voltage of the AC power source;
An input current detector that detects a current value of the AC power supply; an input voltage detector that detects a voltage value of the AC power supply;
A DC voltage detector for detecting a voltage value of a DC voltage output by the AC / DC converter,
Based on the current value of the AC power source, the voltage value of the AC power source, and the voltage value of the DC voltage obtained by the input current detection unit, the input voltage detection unit, and the DC voltage detection unit, respectively, the voltage value of the DC voltage Comprising a switching operation control unit for controlling on / off of the switching element so that becomes a preset output voltage setting value,
The switching operation controller is
A target output voltage calculation unit that generates a target output voltage value that is an upper limit value of on / off control of the voltage value of the DC voltage;
Until the voltage value of the DC voltage reaches the output voltage set value, the target number is the number of steps obtained by dividing the startup processing time for controlling on / off of the preset switching element by the preset update cycle time. A power supply apparatus having a target output voltage calculation unit, wherein target voltage generation control is performed to increase an output voltage value stepwise up to the output voltage set value.   The target output voltage calculation unit takes an average value of the output voltage measurement value Vdc input from the DC voltage detection unit and the start target voltage value Vstart in the previous target output voltage value Vref generation processing flow, and newly The power supply apparatus according to claim 1, wherein a process for obtaining a starting start voltage value Vstart is performed. The AC / DC converter includes a relay circuit between an input terminal to which the AC voltage is input,
The switching operation control unit, the voltage value of the DC voltage before turning on the relay circuit as a start start voltage value,
In a period in which the cycle of the AC voltage is multiplied by a preset number of cycles after the relay circuit is turned on, the average of the voltage value of the DC voltage and the start-up voltage value is updated every update cycle. The starting start voltage value is
After the period of multiplying the cycle of the AC voltage by a preset number of cycles, the voltage difference between the output voltage setting value and the start-up voltage value is divided by the number of steps, and the voltage increase per step The power supply apparatus according to claim 1, wherein the target output voltage value is increased stepwise by calculating the voltage increase. The switching operation controller is
A target output voltage calculation unit for generating a target output voltage value;
A value obtained by normalizing the output voltage measurement value is compared with the target output voltage value, and the difference is taken to generate a voltage difference value, and the voltage difference value is multiplied by the voltage gain to obtain a voltage error signal. A voltage error signal generator to generate,
A multiplier that multiplies the voltage error signal by normalizing the input voltage measurement value to generate an input current set value;
A comparator that compares a value obtained by normalizing an input current measurement value with the input current setting value and generates a current difference value by taking the difference;
A current error signal generator for multiplying the current difference value and the current gain to generate a current error signal;
Based on the current error signal, the pulse width for turning on the switching element is calculated using, for example, an arithmetic expression for converting the current error signal IPI to the duty ratio DUTY, and output to the switching operation control unit. And
The power supply device according to claim 1, further comprising: The switching operation controller is
In the duty ratio calculation unit, by the current error signal IPI obtained in the PID calculation process,
The duty ratio DUTY is
DUTY = Dmax−IPI × Kcnv
(Dmax is the maximum output value (upper limit value) of the time ratio DUTY, and Kcnv is a coefficient for converting the current error signal IPI into the time ratio DUTY.)
The power supply device according to claim 1, wherein the power supply device performs calculation. The PID calculation process in the duty ratio calculation unit is as follows:
The current difference value Ei (t) is
Ei (t) = input current setting value Iref−input current measurement value Iin (t)
Is calculated by
The current error signal IPI = Ui (t) obtained by the PID calculation process is
Ui (t) = Kip × Ei (t) + {Kii × Ei (t−1) + Ui (t−1)} + Kid × {Ei (t) −Ei (t−n)}
(Ui (t−1) is the current error signal IPI obtained in the previous PID calculation process, and Ei (t−1) and Ei (t−n) are the PIDs one time before and n times before, respectively. A current difference value Ei in the arithmetic processing is shown, Ei (t) is a value based on the current processing result, and Kip, Kii, and Kid are proportional (P) coefficient and integral (I) in the PID arithmetic processing, respectively. (The coefficient and differential (D) coefficient are shown.)
The power supply device according to claim 5, wherein the calculation is performed by: The switching operation control unit includes an offset calculation unit that generates an offset value used for offset subtraction processing in the duty ratio calculation unit,
In this offset calculation unit, the offset value Offset is calculated by the difference between the offset determination threshold value THoffset and the voltage error signal VPI.
Offset = (THoffset−VPI) × Koffset
(Koffset is a coefficient value calculated in advance by experiment or simulation, and is a value set in the switching operation control unit.)
The power supply device according to any one of claims 4 to 6, wherein the calculation is performed by the following. In the duty ratio calculation unit, the duty ratio DUTY is determined by the offset value Offset.
DUTY (t) = DUTY (t−1) −Offset
(DUTY (t) is the time ratio DUTY obtained in the current subtraction process, and DUTY (t−1) is the time ratio DUTY obtained in the previous subtraction process.)
The power supply apparatus according to claim 7, wherein the calculation is performed by:

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