Power factor correction power supply

Abstract

The embodiment of the utility model provides a power factor correction power supply, which is used for converting an alternating current power supply into an intermediate power supply and an output power supply. The power factor correction power supply is provided with a pulse width modulation circuit used for converting the intermediate power supply into the output power supply, and a power supply controller used for controlling the pulse width modulation circuit, and comprises a power supply detector used for detecting an alternating current power supply and providing a power supply normal signal; and a protection circuit for controlling the pulse width modulation circuit, characterized in that when the power supply normal signal indicates that the AC power supply is normal, the protection circuit provides an input power supply protection for the intermediate power supply, and when the power supply normal signal indicates that the AC power supply is abnormal, the protection circuit changes or cancels the input power supply protection.

Description

Technical Field

[0001] This utility model generally relates to a power supply with power factor correction, and more particularly to a power factor correction power supply that can extend the output voltage hold-up time. Background Technology

[0002] Power supply units with power factor correction are often used in lighting or high-power electrical applications. On the one hand, a power supply with power factor correction aims to achieve a power factor as close to ideal as 1, making itself approximately a resistive load to the AC mains power supply. On the other hand, the output power provided by a power supply with power factor correction needs to meet the voltage and current specifications required by the output terminal.

[0003] Figure 1 Example shows a power supply 100 with power factor correction. Power supply 100 includes a power factor correction circuit 102 and a pulse width modulation circuit 104. The power factor correction circuit 102 is responsible for correcting the power factor of power supply 100 from AC power supply V. AC Extract electrical energy to establish an intermediate power source V INV The pulse width modulation circuit 104 uses an intermediate power supply V. INV As an input power source, it is used to establish the output power source V. O The power supply 106 supplies power to the load. Simply put, the power factor correction circuit 102 converts the AC power supply V... AC For intermediate power supply V INV The pulse width modulation circuit 104 converts the intermediate power supply V. INV For output power V O .

[0004] Some loads (106) require an AC power supply of V. AC After disappearing or being unplugged, the output power V O The hold-up time T of the continuously maintained output voltage HOLD-UP The minimum value. Figure 1 It also shows that the power supply 100 provides an AC power detection signal ACD to inform the load 106 of the AC power supply V. AC Is this normal? Figure 2 For example Figure 1 Some signal waveforms or logic states in the data. AC power supply V. AC At time t AC-OFF The power supply 100 begins to disappear, possibly because the power plug has become detached from the socket. At the power shortage notification point tS, the power supply 100 notifies the load 106 of the AC power supply V via the AC power detection signal ACD. ACThis is abnormal. The AC power supply V has been lost. AC To provide electrical energy, output power V O The output voltage drops because it cannot be maintained at the drop point tD. Output voltage hold time T HOLD-UP Between the power failure notification point tS and the output voltage drop point tD, the output voltage hold-up time T. HOLD-UP The longer the better, as it gives the load 106 more time to prepare for a power outage. Utility Model Content

[0005] This utility model provides a power factor correction power supply for converting an AC power supply into an intermediate power supply and an output power supply. The power factor correction power supply includes a pulse width modulation circuit and a power controller. The pulse width modulation circuit converts the intermediate power supply into the output power supply. The power controller controls the pulse width modulation circuit and includes a power detector and a protection circuit. The power detector detects the AC power supply and provides a power normal signal. When the power normal signal indicates that the AC power supply is normal, the protection circuit provides input power protection for the intermediate power supply. When the power normal signal indicates that the AC power supply is abnormal, the protection circuit changes or cancels the input power protection. Attached Figure Description

[0006] Figure 1 An example is shown of an existing power supply with power factor correction.

[0007] Figure 2 For example Figure 1 Some signal waveforms or logic states in the data.

[0008] Figure 3 An example is shown of a power supply with power factor correction according to the present invention.

[0009] Figure 4 Examples include a pulse width modulation circuit and a power controller.

[0010] Figure 5 For example Figure 3 and 4 Some signal waveforms or logic states in the data.

[0011] Figure 6 enlarge Figure 5 High-voltage signal V near the power outage notification point tS HV With normal power supply signal PG.

[0012] [Symbol Explanation]

[0013] 100, 200: Power supply

[0014] 102, 202: Power factor correction circuit

[0015] 104, 204: Pulse Width Modulation Circuit

[0016] 106, 206: Load

[0017] 208: Power Controller

[0018] 210: Optical Coupler

[0019] 212, 214, 216: Resistors

[0020] 218: PMOS transistor

[0021] 230: Comparator

[0022] 234: Voltage divider circuit

[0023] 236, 238: Capacitors

[0024] 240: Comparator

[0025] 242: Power Supply Detector

[0026] 243: and the door

[0027] 244: Reference Voltage Generator

[0028] 246: Protection Circuit

[0029] ACD: AC power detection signal

[0030] CR: Resonant capacitor

[0031] GNDI: Input ground wire

[0032] GNDO: Output ground wire

[0033] HI: Signal

[0034] HS: Power Switch

[0035] HV: High voltage end

[0036] INV: Intermediate power cord

[0037] LO: signal

[0038] LP: Primary winding

[0039] LR: Inductance

[0040] LS: Power Switch

[0041] OUT: Output power line

[0042] PG: Power supply normal signal

[0043] PGI: Reverse Normal Signal

[0044] S BO Undervoltage signal

[0045] S OCP Overcurrent signal

[0046] t AC-OFF Time point

[0047] tD: Output drop point

[0048] tS: Power Outage Notification Point

[0049] T CYC T M Oscillation cycle

[0050] T DB Delay time

[0051] T HOLD-UP Output voltage hold time

[0052] T VLY : Valley Time

[0053] T UV Undervoltage time

[0054] V AC AC power supply

[0055] V AC-AMP AC voltage amplitude

[0056] V BO-REF Undervoltage reference voltage

[0057] V HV High voltage signal

[0058] V HV-PEAK Peak value

[0059] V INV Intermediate power supply

[0060] V O Output power

[0061] V OCP-REF Current reference signal

[0062] V OFF-REF Power shortage reference voltage

[0063] VS: Current detection signal Detailed Implementation

[0064] In this specification, some identical symbols are used to represent components that have the same or similar structure, function, or principle, and which can be deduced by those with ordinary knowledge in the industry based on the teachings of this specification. For the sake of brevity, components with the same symbols will not be repeated.

[0065] According to one embodiment of the present invention, a power factor correction power supply converts an AC power supply into an intermediate power supply and an output power supply. The power factor correction power supply has a pulse width modulation circuit for converting the intermediate power supply into the output power supply. The power factor correction power supply detects the AC power supply to provide a power normality signal, which can be converted into an AC power detection signal for a load. In this embodiment, an output voltage holding time begins at a power shortage notification point where the load detects an abnormal AC power supply via the AC power detection signal and ends at an output voltage drop point where the output power supply can no longer maintain a default voltage.

[0066] One embodiment of this invention utilizes two methods to extend the output voltage holding time. One method is to notify the load of the power failure as early as possible, that is, to inform the load that the AC power supply is abnormal as early as possible. The other method is to deplete the intermediate power supply as much as possible to maintain the output power and delay the output drop-off point.

[0067] Figure 3 For example, according to the present invention, a power supply 200 with power factor correction has a power factor correction circuit 202 and a pulse width modulation circuit 204. Figure 3 and 1 Similarities or resemblances can be learned from previous teachings and will not be repeated here. Figure 3 In the middle, the AC power supply V AC With intermediate power supply V INV On the primary side, the output power supply V O On the secondary side, the primary and secondary sides are electrically isolated from each other. The primary side's 0V is based on the voltage across the input ground wire GNDI; the secondary side's 0V is based on the voltage across the output ground wire GNDO. Intermediate power supply V INV Roughly located at the intermediate power line INV. Output power V O It is roughly located on the output power line OUT.

[0068] On the primary side, two diodes and resistor 212 are connected to the AC power supply V. AC Rectification generates a high-voltage signal V at the high-voltage end HV. HV The power controller 208 operates based on the high-voltage signal V. HV Test AC power supply VAC The PMOS transistor 218 generates a normal power signal PG. The normal power signal PG controls the PMOS transistor 218 to generate an inverted normal signal PGI. Through the PMOS transistor 218, resistors 214 and 216, and optocoupler 210, the normal power signal PG on the primary side is converted into an AC power detection signal ACD on the secondary side and sent to the load 206.

[0069] Figure 4 An example is shown of a pulse width modulation circuit 204 and a power controller 208. The power controller 208 provides signals HI and LO to control the pulse width modulation circuit 204.

[0070] The pulse width modulation circuit 204 is essentially an LLC power converter, featuring power switches HS and LS forming a half-bridge, a resonance circuit consisting of inductor LR, primary winding LP, and resonant capacitor CR, and a voltage divider 234 consisting of capacitors 236 and 238, connected as follows: Figure 4 As shown. The voltage divider circuit 234 provides a current sensing signal VS, which roughly represents the intermediate power supply V. INV Provide one of the input currents to the pulse width modulation circuit 204.

[0071] The power controller 208 includes a power detector 242 and a protection circuit 246. The power detector 242 receives a high-voltage signal V. HV To test AC power supply V AC This is used to provide a power supply normal signal PG. In one embodiment, a power supply normal signal PG with a logic value of "1" indicates that the AC power supply V... AC Normal; a normal power supply signal PG with a logic value of "0" indicates AC power supply V. AC An anomaly, possibly a power outage.

[0072] Protection circuit 246 provides two types of input power protection: INV overcurrent protection and INV undervoltage protection. INV overcurrent protection refers to limiting the pulse width modulation circuit 204's protection of the intermediate power supply V. INV The current drawn. INV undervoltage protection (Brownout protection) refers to limiting the pulse width modulation circuit 204 to only operate under the intermediate power supply V. INV The power supply is switched only when there is sufficient voltage.

[0073] Comparator 230 compares the overcurrent reference signal V OCP-REF The current detection signal VS is used to limit the pulse width modulation circuit 204 to the intermediate power supply V. INVThe extracted current provides INV overcurrent protection. In one embodiment, when the current detection signal VS is greater than the overcurrent reference signal V... OCP-REF At that time, the overcurrent signal S OCP The INV overcurrent protection is triggered, and logic control 232 turns off the power switch HS, allowing the pulse width modulation circuit 204 to enter the next switching cycle. For example, after the power switch HS turns off, the power switch LS turns on.

[0074] Comparator 240 compares the intermediate power supply V INV and undervoltage reference voltage V BO-REF Used to check the intermediate power supply V INV Is the voltage too low? Provide INV undervoltage protection. (Regarding AC power supply V...) AC Under normal conditions, the normal power signal PG is "1", and AND gate 243 can transmit the undervoltage signal S output by comparator 240. BO To logic control 232. Once the intermediate power supply V INV Below the undervoltage reference voltage V BO-REF Logic control 232 continuously shuts off power switches HS and LS, stopping the power conversion of pulse width modulation circuit 204, until the intermediate power supply V... INV The voltage has been restored to a sufficient level.

[0075] According to one embodiment of the present invention, when the AC power supply V AC In case of an abnormality, the normal power supply signal PG is "0", the INV overcurrent protection provided by protection circuit 246 is relaxed, and the INV undervoltage protection is released. In other words, the intermediate power supply V INV The voltage can be lower, and the intermediate power supply V INV The current supplied to the pulse width modulation circuit 204 can be larger. This means that, compared to the AC power supply V, the current can be increased. AC Normally, once the AC power supply V... AC An error occurred; the pulse width modulation circuit 204 was allowed to operate from the intermediate power supply V. INV A relatively large amount of electrical energy is drawn to maintain the output power supply V. O This allows for a longer output voltage hold-up time.

[0076] The reference voltage generator 244 provides an overcurrent reference signal V based on the normal power supply signal PG. OCP-REF In one embodiment, the overcurrent reference signal V is used when the power supply normal signal PG is "1". OCP-REF The overcurrent reference signal V is less than when the normal power supply signal PG is "0". OCP-REF In other words, when the alternating current power supply V... AC In case of an anomaly, the reference voltage generator 244 increases the overcurrent reference signal V.OCP-REF This relaxes the INV overcurrent protection. In one embodiment, the overcurrent reference signal V is used when the power supply normal signal PG is "0". OCP-REF It is approximately 1.3 times the value when the power supply signal PG is "1".

[0077] When the normal power signal PG is "0", AND gate 243 permanently blocks the undervoltage signal S output by comparator 240. BO This prevents it from being received by logic control 232, thus disabling the INV undervoltage protection.

[0078] Figure 5 For example Figure 3 and 4 Some signal waveforms or logic states are used to illustrate some of the operating actions of the power supply 200.

[0079] as Figure 5 As shown, AC power supply V AC At time t AC-OFF It begins to disappear. (In the AC power supply V) AC Normally, the high-voltage signal V at the high-voltage end HV is... HV It has an M-type waveform with a peak value V. HV-PEAK It is approximately equal to the AC power supply V. AC AC voltage amplitude V AC-AMP Power detector 242 compares the high voltage signal V. HV With the power shortage reference voltage V OFF-REF In high voltage signal V HV The voltage remains below the low-voltage reference voltage V OFF-REF At the power outage notification point tS, after the power outage occurs, the power detector 242 sets the normal power signal PG to "0" and the reverse normal signal PGI to "1". Therefore, approximately at the power outage notification point tS, the secondary-side load 206 detects the AC power supply V through the AC power detection signal ACD. AC This is no longer normal.

[0080] as Figure 5 As shown, the output voltage hold time T HOLD-UP From the power failure notification point tS to the output power supply V O The output drops to point tD when it can no longer be maintained.

[0081] Figure 5 It also shows the AC power supply V AC Under normal conditions (before the power failure notification point tS), the power controller 208 provides INV undervoltage protection (brownout protection) and INV overcurrent protection through comparators 230 and 240. (Similar to...) Figure 5 It also shows that the AC power supply V AC When an anomaly is confirmed (after the power failure notification point tS), the INV undervoltage protection is deactivated, while the INV overcurrent protection is relaxed, as if... Figure 4 The result is due to the AND gate 243 and the reference voltage generator 244. The release of INV undervoltage protection and the relaxation of INV overcurrent protection can delay the occurrence of the output dropout point tD, which is equivalent to extending the output voltage hold-up time T. HOLD-UP .

[0082] Figure 6 enlarge Figure 5 High-voltage signal V near the power outage notification point tS HV With normal power supply signal PG. At AC power supply V AC Under normal conditions, the AC power supply V AC With oscillation period T CYC Approximately the high-voltage signal V HV The oscillation period T M Twice that. In the following example, the AC power supply V... AC Under normal circumstances, the oscillation period T CYC The oscillation period is 20ms and the oscillation period is T. M For 10ms, and AC voltage amplitude V AC-AMP With peak V HV-PEAK Both are 127V (=90V*1.414) and the power shortage reference voltage V. OFF-REF It is 63.5V (equal to the AC voltage amplitude V) AC-AMP (1 / 2). But these are just examples and are not intended to limit the utility model. Figure 6 In the middle, the trough time T VLY To obtain from high voltage signal V HV Below the power shortage reference voltage V OFF-REF From the beginning, to the high-voltage signal V HV The rebound voltage exceeded the power shortage reference voltage V. OFF-REF End. In one embodiment, the power-off reference voltage V OFF-REF AC voltage amplitude V AC-AMP 1 / 2, trough time T VLY The oscillation period is 3.33ms (T). M (1 / 3 of it).

[0083] Figure 4 The power detector 242 compares the high voltage signal V. HV With the power shortage reference voltage V OFF-REF To generate the power supply normal signal PG. Figure 6 In the middle, when the high voltage signal V HV Below the power shortage reference voltage V OFF-REFPower detector 242 starts timing the undervoltage time T. UV When the high voltage signal V HV Higher than the power shortage reference voltage V OFF-REF Undervoltage time T UV Reset to 0. During the undervoltage time T UV Exceeding the preset delay time T DB Subsequently, the power detector 242 changed the normal power signal PG to indicate the AC power supply V. AC Abnormal, like Figure 6 As shown. Under normal conditions, the undervoltage time T UV It should be approximately equal to the trough time T. VLY When the undervoltage time T UV Exceeding the trough time T VLY At that time, this could mean that the alternating current power supply V AC It has completely disappeared, so it can be concluded that the AC power source V... AC This is abnormal. To prevent misjudgment, the scheduled delay time T... DB Best compared to the trough time T VLY Long, which can be the trough time T VLY Twice that. In one embodiment, the delay time T DB At least the oscillation period T M One-third of, but no greater than one oscillation period T. M In other words, in one embodiment, the delay time T DB The oscillation period T is approximately between 1 / 6 and 1 / 2 of the total oscillation period. CYC .

[0084] In the embodiment, the power shortage reference voltage V OFF-REF Ideally, it should be less than or equal to the AC voltage amplitude V. AC-AMP 1 / 2. From Figure 6 It can be seen that in the alternating current power source V AC Under normal conditions, the voltage shortage reference voltage V OFF-REF The smaller the value, the shorter the trough time T. VLY The shorter the length, the sooner the power detector 242 can detect the AC power source V. AC An anomaly can be detected, and the power failure notification point tS can be earlier. An earlier power failure notification point tS implies a longer output voltage hold-up time T. HOLD-UP .

[0085] The output voltage hold-up time T of an existing power factor correction power supply HOLD-UP The duration is 30ms. After adopting the improvement of this embodiment, the output voltage holding time T is... HOLD-UP It can be significantly extended, reaching 64ms.

[0086] The above description is only a preferred embodiment of the present utility model. All equivalent changes and modifications made within the scope of the claims of the present utility model shall be covered by the present utility model.

Claims

1. A power factor correction power supply for converting an AC power supply into an intermediate power supply and an output power supply, comprising: A pulse width modulation circuit is used to convert the intermediate power supply into the output power supply; and A power controller for controlling the pulse width modulation circuit, comprising: A power supply detector detects the AC power supply to provide a power supply normality signal; and A protection circuit controls the pulse width modulation circuit, characterized in that, When the power supply normal signal indicates that the AC power supply is normal, the protection circuit provides input power protection for the intermediate power supply, and when the power supply normal signal indicates that the AC power supply is abnormal, the protection circuit changes or cancels the input power protection.

2. The power factor correction power supply as described in claim 1, further comprising: A rectifier circuit is used to rectify the AC power supply to provide a high-voltage signal having a peak value; Its features are, The power detector compares the high-voltage signal with a power-out reference voltage to generate the power-normal signal, wherein the power-out reference voltage is not greater than half of the peak value.

3. The power factor correction power supply as described in claim 1, characterized in that, The protection circuit includes: A reference voltage generator provides an overcurrent reference signal when the power supply normal signal indicates that the AC power supply is normal; and A comparator compares the overcurrent reference signal with a current detection signal, wherein the current detection signal represents the input current provided by the intermediate power supply to one of the pulse width modulation circuits. The feature is that when the power supply normal signal indicates that the AC power supply is abnormal, the reference voltage generator increases the overcurrent reference signal.

4. The power factor correction power supply as described in claim 1, characterized in that, The protection circuit includes: A comparator compares the intermediate power supply with an undervoltage reference voltage; and A logic control that can receive the output of one of the comparators; The characteristic feature is that when the power supply normal signal indicates that the AC power supply is abnormal, the output cannot be received by the logic control.

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