TWI478476B - Compensation of average inductor current control using variable reference voltage - Google Patents

Description

Average inductor current type voltage compensation control device and control method thereof

The present invention relates to a control technique, and more particularly to an average inductor current type voltage compensation control device and a control method thereof.

Voltage converters can be roughly divided into several types according to different types, AC to AC converters, AC to DC converters, DC to DC converters, and DC to DC (DC). /AC); Among them, in the case of DC-to-DC converters, in many electronic circuits, there are often some electronic components that require power supplies other than dual power supplies, such as liquid crystal displays, voltage comparators, operational amplifiers, etc. Or because multiple sets of electronic components have different operating voltages and different sets of different potentials, a DC-to-DC converter is needed to obtain the desired voltage.

As shown in FIG. 1 , the DC-to-DC converter 10 includes a capacitor 12 , a diode 14 , an inductor 16 , a transistor switch 18 , and a resistor 20 . The switching state of the transistor switch 18 is controlled by a feedback. Controlled by controller 22. During the ON state of the transistor switch 18, the input power source 24 has a current flowing through the inductor 16 to store energy on the inductor 16; and when the transistor switch 18 receives the cutoff signal, the transistor switch 18 is turned off (OFF). At this time, the induced current on the inductor 16 is discharged to the resistor 20 to stabilize the output of the sustain voltage. The feedback controller 22 can detect the current on the inductor 16 and thereby control the transistor switch 18, wherein the feedback controller 22 generates a control signal for controlling the transistor switch 18, and a current waveform on the inductor 16 such as Figure 2 shows. In the waveform of the inductor current, the peak current value is equal to the double average inductor current value minus the valley current value, and in the above control signal, the time interval of the low level voltage is fixed. With the above negative feedback control method, when the input power source 24 is increased to several hundred volts, the peak current value and the valley current value will no longer remain fixed and vary, and in order to fix the average inductor current, the lower the valley current value, the peak The higher the current value; the higher the valley current value, the lower the peak current value. In addition, the measurement waveform is as shown in FIG. 3, wherein the dotted waveform is the source voltage waveform of the transistor switch 18, Below is the current waveform and inductor current waveform through the diode string 26. It can be seen that the peak value and the valley value of the inductor current are constantly changing.

Therefore, the present invention has been made in view of the above problems, and an average inductor current type voltage compensation control apparatus and a control method thereof are provided to solve the problems caused by the conventional method.

The main object of the present invention is to provide an average inductor current type voltage compensation control device and a control method thereof, which utilize an average valley voltage of at least two adjacent time points on an inductance, and an average inductor current corresponding to a double inductor. Two times the external voltage to fix the peak current on the inductor, and does not need to sense the high side of the induced current, and at the same time avoid the independent inductance in the DC-to-DC converter to improve the accuracy of voltage adjustment. .

To achieve the above objective, the present invention provides an average inductor current type voltage compensation control apparatus including a valley voltage sampling and holding unit for connecting an inductance of the DC-to-DC converter through an electronic switch in a DC-to-DC converter. And receiving at least two valley currents of at least two adjacent time points on the inductor and converting them into an average valley voltage. The valley voltage sampling and holding unit and the electronic switch in the DC-DC converter are simultaneously connected to a reference voltage generator through a comparator, which receives and receives twice the external voltage corresponding to the average inductor current of the double inductor to reduce it. The average valley voltage is de-energized to produce a reference voltage to control the electronic switch to thereby maintain a constant peak current across the inductor.

The invention also provides an average inductor current type voltage compensation control method for controlling a DC-to-DC converter, the DC-DC converter comprising an electronic switch and an inductor. First, receiving at least two external current voltages corresponding to the average inductor current of the double inductor and at least two valley currents at at least two adjacent time points on the inductor, and converting at least the two valley currents into an average valley voltage. Next, the average external voltage is subtracted from the average valley voltage to output a reference voltage of one of the control electronic switches.

For a better understanding and understanding of the structural features and the achievable effects of the present invention, please refer to the preferred embodiment and the detailed description.

Since the inductor chopping current is controlled by the valley inductor current plus half of the sum of the peak inductor currents, this means that the peak inductor current Ipeak is equal to twice the average inductor current Iavg minus the valley inductor current Ivally, as in equation (1). Show. However, in order to fix the peak inductor current Ipeak, the present invention modifies the above-mentioned valley inductor current Ivally to the average of the valley inductor currents Iv1 and Iv2 adjacent to at least two time points, as shown in the formula (2), to avoid the valley value. The variation of the inductor current Ivally is calculated. According to the above principle, the present invention subtracts the average value of the valley voltages Vh1 and Vh2 of at least two adjacent time points on the inductance corresponding to the external voltage Vext of the average inductor current of the double inductor, and the average value is the valley value. The average valley voltages of the voltages Vh1 and Vh2 are subtracted to obtain a reference voltage Vref, as shown in the equation (3), and the peak inductor current Ipeak is fixed accordingly.

Ipeak=2*Iavg-Ivally (1)

Ipeak=2*Iavg-(Iv1+Iv2)/2 (2)

Vref=2*Vext-(Vh1+Vh2)/2 (3)

Please refer to Figure 4 below. The present invention is coupled to a DC-to-DC converter 28 having a fixed off-time, comprising an inductor 30 and an electronic switch. In the present embodiment, the electronic switch is exemplified by a transistor switch 32. The present invention includes a valley voltage sample and hold unit 34 and a reference voltage generator 36. The valley voltage sample and hold unit 34 is coupled to the inductor 30 through the transistor switch 32 and receives at least two adjacent time points on the inductor 30. The valley current is converted to an average valley voltage. The reference voltage generator 36 is connected to the valley voltage sample holding unit 34 and the transistor switch 32, and receives twice the external voltage Vext corresponding to the average inductor current Iave of the double inductor 30 to subtract the average valley voltage thereof to generate a Reference voltage Vref. The inductor 30, the valley voltage sample and hold unit 34, the reference voltage generator 36 and the transistor switch 32 are all connected to a comparator 38, which receives the reference voltage Vref and the inductor voltage of the inductor 30, and controls the transistor according to the comparison result. Switch 32 is thereby used to maintain the peak current constant.

In other words, the operation of the present invention is as follows. First, the reference voltage generator 36 receives twice the external voltage Vext corresponding to the average inductor current Iave of the double inductor 30, and The valley voltage sample hold unit 34 receives at least two valley currents of at least two adjacent time points on the inductor 30 and converts at least two valley currents into an average valley voltage. Next, the reference voltage generator 36 subtracts the received double external voltage Vext from the average valley voltage to generate a reference voltage Vref that controls the transistor switch 32. Finally, the comparator 38 receives the reference voltage Vref and the inductor voltage of the inductor 30, and according to the result of the comparison, controls the transistor switch 32 to thereby maintain the peak current on the inductor 30 constant. For example, when the comparison result is that the reference voltage and the inductor voltage are the same, the transistor switch 32 is turned off; when the comparison result is that the reference voltage is different from the inductor voltage, the transistor switch 32 is turned on. The comparator 38 generates a control signal for controlling the transistor switch 32, and the current waveform on the inductor 30 is as shown in FIG. 5, wherein the time interval of the high level voltage of the control signal is fixed, and the peak current on the inductor 30 is The valley current also becomes fixed. In addition, the measurement waveform is as shown in FIG. 6, wherein the dotted waveform is the source voltage waveform of the transistor switch 32, and the current waveform of the current waveform and the inductor 30 passing through the diode string 40 is sequentially followed. It can be seen that the peak value and the valley value of the inductor current are already fixed. In this way, the present invention eliminates the need to sense the high side induced current while avoiding the influence of the independent inductance in the DC-to-DC converter to improve the accuracy of the voltage adjustment.

In the above process, if the present invention lacks the comparator 38, the step of receiving the reference voltage Vref and the inductance of the inductor 30 may be omitted, and the step of controlling the transistor switch 32 may be performed according to the comparison result.

Referring to FIG. 4, the specific circuit of the valley voltage sample-and-hold unit 34 and the reference voltage generator 36 will be further described below.

The two valley currents respectively comprise a first valley current and a second valley current corresponding to one of the first and last time points, and the average valley voltage is one of the first valley current and the second valley current respectively. The sum of the half valley voltage and a second half valley voltage. The valley voltage sample holding unit 34 here only includes the two sub-valley voltage sample holding unit 37 to respectively extract the first half bottom voltage and the second half bottom voltage. The sub-valley voltage sample and hold unit 37 further includes a first timing switch 42 and a first valley voltage holding unit 44, and the other sub-valley voltage sample and hold unit 37 further includes a second timing switch 46 and a Second valley Voltage holding unit 48. The first timing switch 42 is connected to the inductor 30 and is temporarily turned on at two adjacent time points to respectively pass the first valley current and the second valley current. The first timing switch 42 is coupled to the first valley voltage holding unit 44, which receives the first valley current or the second valley current from the first timing switch 42 and converts it into the first half valley voltage, respectively. Or the second half of the valley voltage and maintain its output. The first valley voltage holding unit 44 is connected to the second timing switch 46, which is between two adjacent time points, and when the inductor current gradually decreases, is temporarily turned on as the transmission path of the first half-valley voltage. The second timing switch 46 is coupled to a second valley voltage holding unit 48 that receives the first half-valley voltage from the second timing switch 46 and maintains its output.

The on state of the first timing switch 42 and the second timing switch 46 is controlled by a timing controller 49. The first timing switch 42 and the second timing switch 46 are connected to the inductor 30 to the timing controller 49, which temporarily turns on the first timing switch 42 at two adjacent time points, and between two adjacent time points, and When the inductor current gradually decreases, the second timing switch 46 is temporarily turned on.

The first valley voltage holding unit 44 further includes a first amplifier 50 connected to the first timing switch 42 to receive the first valley current or the second valley current, respectively outputting a first communication number or a first Second guide communication number. The first amplifier 50 is coupled to the reference voltage generator 36 to a first transistor switch 52 that receives the first pilot or second pilot to maintain conduction. There is a first capacitor 54 and a first resistor 56. One end of the first capacitor 54 is grounded, and the other end is connected to the first timing switch 42 and the first amplifier 50. One end of the first resistor 56 is grounded, and the other end is connected to the first transistor switch 52 and the first amplifier 50. The first capacitor 54 and the first resistor 56 receive the first valley current or the second valley through the first timing switch 42. The current is converted to a first half valley voltage or a second half valley voltage to maintain a first half valley voltage or a second half valley voltage output by the first transistor switch 52.

The second valley voltage holding unit 48 further includes a second amplifier 58 connected to the second timing switch 46 for receiving the first half-valley voltage and outputting a third pilot signal. The second amplifier 58 is coupled to the reference voltage generator 36 to a second transistor switch 60 that receives the third pilot signal to maintain conduction. There is a second capacitor 62 and a second resistor 64. One end of the second capacitor 62 is grounded, and the other end is connected to the second timing switch 46 and the second amplifier 58. One end of the second resistor 64 is grounded, and the other end is connected to the second transistor switch 60 and the second amplifier 58, the second resistor 64 has the same resistance as the first resistor 56, and the second capacitor 62 and the second resistor 64 pass through the second timing. Switch 46 receives the first half-valley voltage to maintain output of the first half-valley voltage by second transistor switch 60.

The reference voltage generator 36 further includes a third amplifier 66 that receives twice the external voltage Vext to generate a fourth pilot number. The third amplifier 66 is connected to one end of a third resistor 68, and the other end of the third resistor 68 is grounded. Further, the resistance of the third resistor 68 is half of the first resistor 56. The third amplifier 66 and the third resistor 68 are connected to a third transistor switch 70, which receives the fourth conduction number and is generated by the third resistor 68 to flow twice the third transistor 70 and the third resistor 68. Average inductor current Iave. The third transistor switch 70 is further connected to a current mirror 72. The current mirror 72 is connected to one end of a fourth resistor 74, and the other end of the fourth resistor 74 is grounded. The resistance of the fourth resistor 74 is the same as that of the third resistor 68. The current mirror 72 replicates the double average inductor current Iave to generate a double-average inductor current Iave through the fourth resistor 74, and thereby generates a double external voltage Vext to subtract the two-half valley voltage to successfully generate the reference voltage. Vref.

The above embodiment only receives the two valley currents to form an average valley voltage. Referring to FIG. 7 below, this embodiment differs from the above embodiment in that the valley voltage sample holding unit 34 includes a plurality of sub-valley voltage samples and samples. Unit 37. Therefore, in this embodiment, the valley voltage sample holding unit 36 receives the complex valley current of the complex adjacent time points on the inductance and converts it into an average valley voltage such that the average valley voltage Vave is The sum of the valley voltages Vhn corresponding to a valley current is averaged as shown in equation (4). The rest of the circuit architecture and its operation are the same as the foregoing embodiments, and details are not described herein again.

Vave=(Vh1+Vh2+...+Vhn)/n (4)

In summary, the present invention uses the inductor valley current of two adjacent time points to fix the peak current of the inductor, thereby improving the accuracy of the DC-to-DC converter.

The above is only a preferred embodiment of the present invention, and is not intended to limit the scope of the present invention, so that the shapes, structures, features, and spirits described in the claims of the present invention are equally varied and modified. , should be included in the scope of patent application of the present invention Inside.

10‧‧‧DC to DC converter

12‧‧‧ Capacitance

14‧‧‧ diode

16‧‧‧Inductance

18‧‧‧Transistor Switch

20‧‧‧resistance

22‧‧‧Return controller

24‧‧‧Input power supply

26‧‧‧Diode string

28‧‧‧DC to DC converter

30‧‧‧Inductance

32‧‧‧Transistor Switch

34‧‧‧ Valley Voltage Sampling and Holding Unit

36‧‧‧Reference voltage generator

37‧‧‧Sub-valley voltage sampling and holding unit

38‧‧‧ comparator

40‧‧‧Diode string

42‧‧‧First timing switch

44‧‧‧First valley voltage holding unit

46‧‧‧Second timing switch

48‧‧‧second valley voltage holding unit

49‧‧‧Sequence Controller

50‧‧‧First amplifier

52‧‧‧First transistor switch

54‧‧‧first capacitor

56‧‧‧First resistance

58‧‧‧Second amplifier

60‧‧‧Second transistor switch

62‧‧‧second capacitor

64‧‧‧second resistance

66‧‧‧3rd amplifier

68‧‧‧ Third resistor

70‧‧‧ Third transistor switch

72‧‧‧current mirror

74‧‧‧fourth resistor

Figure 1 is a circuit diagram of a prior art DC-to-DC converter.

Figure 2 is a voltage waveform diagram of the prior art inductor current and control transistor switch.

Figure 3 is a diagram showing the source voltage, diode string current, and inductor current waveform of a prior art transistor switch.

Figure 4 is a circuit diagram of a control device for receiving two valley currents according to the present invention.

Figure 5 is a voltage waveform diagram of the inductor current and the control transistor switch of the present invention.

Figure 6 is a waveform diagram of the source voltage, the diode string current, and the inductor current of the transistor of the present invention.

Figure 7 is a circuit diagram of a control device for receiving a complex valley current according to the present invention.

28‧‧‧DC to DC converter

30‧‧‧Inductance

32‧‧‧Transistor Switch

34‧‧‧ Valley Voltage Sampling and Holding Unit

36‧‧‧Reference voltage generator

38‧‧‧ comparator

37‧‧‧Sub-valley voltage sampling and holding unit

40‧‧‧Diode string

42‧‧‧First timing switch

44‧‧‧First valley voltage holding unit

46‧‧‧Second timing switch

48‧‧‧second valley voltage holding unit

49‧‧‧Sequence Controller

50‧‧‧First amplifier

52‧‧‧First transistor switch

54‧‧‧first capacitor

56‧‧‧First resistance

58‧‧‧Second amplifier

60‧‧‧Second transistor switch

62‧‧‧second capacitor

64‧‧‧second resistance

66‧‧‧3rd amplifier

68‧‧‧ Third resistor

70‧‧‧ Third transistor switch

72‧‧‧current mirror

74‧‧‧fourth resistor

Claims (16)

An average inductor current type voltage compensation control device is connected to a DC-to-DC converter, and the average inductor current type voltage compensation control device comprises: a valley voltage sampling and holding unit connected to one of the DC-DC converters And receiving at least two valley currents of the at least two adjacent time points on the inductor and converting them into an average valley voltage; and a reference voltage generator connecting the valley voltage sample holding unit and the DC pair An electronic switch in the DC converter, and receiving twice the external voltage corresponding to the average inductor current of the inductor to subtract the average valley voltage, generating a reference voltage to control the electronic switch, thereby Keep the peak current on the inductor constant. The average inductor current type voltage compensation control device according to claim 1, wherein the DC to DC converter is a DC-to-DC converter with a fixed off time. The average inductor current type voltage compensation control device of claim 1, further comprising a comparator connecting the inductor, the valley voltage sample and hold unit, the reference voltage generator and the electronic switch to receive the reference The voltage and the inductor voltage of the inductor, and based on the comparison thereof, control the electronic switch to thereby maintain the peak current at the constant value. The average inductor current type voltage compensation control device of claim 3, wherein when the reference voltage is different from the inductor voltage, the comparator turns on the electronic switch to thereby cause the peak current to reach the predetermined value. The average inductor current type voltage compensation control device of claim 3, wherein the comparator turns off the electronic switch when the reference voltage is the same as the inductor voltage. The average inductor current type voltage compensation control device of claim 1, wherein the two valley currents comprise a first valley current and a second valley current corresponding to the first and subsequent time points, respectively, the average valley The value voltage is a sum of a first valley voltage and a second valley voltage respectively corresponding to the first valley current and the second valley current, and the valley voltage sampling and holding unit further comprises: a first a timing switch, connected to the inductor, and temporarily turned on at the two adjacent time points to respectively pass the first valley current and the second valley current; a first valley voltage holding unit connected to the first timing switch to receive the first valley current or the second valley current and convert it into the first valley voltage or the second a half-valley voltage, and maintaining its output; a second timing switch connected to the first valley voltage holding unit, and between the two adjacent time points, and the inductor current gradually decreases, temporarily turning on a transmission path of the first half of the valley voltage; and a second valley voltage holding unit connected to the second timing switch to receive the first half-valley voltage and maintain its output. The average inductor current type voltage compensation control device of claim 6, wherein the first valley voltage holding unit further comprises: a first amplifier connected to the first timing switch to receive the first valley current or The second valley current respectively outputs a first communication number or a second communication number; a first transistor switch is connected to the first amplifier and the reference voltage generator, and receives the first communication number or the first a second conductivity communication number to maintain conduction; a first capacitor, one end of which is grounded, the other end is connected to the first timing switch and the first amplifier; and a first resistor, one end of which is grounded, and the other end is connected to the first transistor switch And the first amplifier, the first capacitor and the first resistor receive the first valley current or the second valley current through the first timing switch, and converts the first valley voltage or the first valley voltage or The second half-valley voltage is maintained to output the first half-valley voltage or the second half-valley voltage by the first transistor switch; and the second valley voltage holding unit further comprises: a second amplifier, Connecting the second timing switch to receive the first half-valley voltage, outputting a third communication number; a second transistor switch connecting the second amplifier and the reference voltage generator, and receiving the third communication number To maintain conduction; a second capacitor having one end grounded and the other end connected to the second timing switch and the second amplifier; a second resistor having one end connected to the ground and the other end connected to the second transistor switch and the second amplifier, wherein the second resistor has the same resistance as the first resistor, and the second capacitor and the second resistor pass through the second resistor The second timing switch receives the first half-bottom voltage to maintain the output of the first half-valley voltage by the second transistor switch. The average inductor current type voltage compensation control device of claim 7, wherein the reference voltage generator further comprises: a third amplifier receiving the double external voltage to generate a fourth communication number; a third resistor, The resistance is half of the first resistor, one end of the third resistor is grounded, and the other end is connected to the third amplifier; a third transistor switch is connected to the third amplifier and the third resistor to receive the fourth Transmitting a communication number, and generating, by the third resistor, the average inductor current flowing through the third transistor switch and the third resistor; a current mirror connecting the third transistor switch; and a fourth resistor, The resistance is the same as the third resistance, one end of the fourth resistor is grounded, and the other end is connected to the current mirror, and the current mirror copies the average inductor current twice to generate the average inductance by twice the fourth resistance. The current is generated, and the double external voltage is generated accordingly to subtract the two half-valley voltage to generate the reference voltage. The average inductor current type voltage compensation control device of claim 6, further comprising a timing controller that connects the first timing switch, the second timing switch and the inductor, and at the two adjacent time points The first timing switch is turned on temporarily, and the second timing switch is temporarily turned on when the inductor current gradually decreases between the two adjacent time points. The average inductor current type voltage compensation control device according to claim 1, wherein when the time point and the valley current are both plural, the average valley voltage is a sum of the average of the valley voltages corresponding to each of the valley currents. . An average inductor current type voltage compensation control method is for controlling a DC-to-DC converter, the DC-DC converter includes an electronic switch and an inductor, and the average inductor current type voltage compensation control method comprises the following steps: receiving corresponding two Double the average inductor current of the inductor and double the external voltage with the inductor At least two valley currents of at least two adjacent time points, and converting the at least two valley currents into an average valley voltage; and subtracting the average external voltage from the average external voltage to output the electronic switch One of the reference voltages. The method for controlling an average inductor current type voltage compensation according to claim 11, further comprising a step of receiving the reference voltage and an inductance voltage of the inductor, and controlling the electronic switch according to the comparison result, thereby The peak current on the inductor remains constant. The average inductor current type voltage compensation control method according to claim 12, wherein the comparison result is that the reference voltage is the same as the inductor voltage, the electronic switch is turned off. The method of claim 12, wherein the comparison result is that the reference voltage is different from the inductor voltage, the electronic switch is turned on to thereby maintain the peak current at the constant value. The method for controlling an average inductor current type voltage compensation according to claim 11, wherein the DC-to-DC converter is a DC-to-DC converter with a fixed off-time. The method of claim 11, wherein the average valley voltage is a sum of the valley voltages corresponding to each of the valley currents. .