TWI420792B - Resonant converters and burst mode control methods thereof - Google Patents

Description

Resonant converter and its intermittent mode control method

This invention relates to power supplies, and more particularly to a resonant converter employing intermittent control.

In recent years, due to the purpose of energy saving and environmental protection, the power supply has been developed in the direction of high efficiency, high power density, high reliability and low cost. The resonant type converter has high soft switching characteristics and operates in a duty cycle state, so it is highly efficient at full load and is favored by many people. However, resonant converters are not as efficient at light loads.

In order to overcome this problem, the conventional technique operates the resonant type converter in a batch mode to reduce the number of switching times and total loss per unit time, so that the efficiency can be improved. For example, as shown in FIG. 1, in the intermittent operation mode, when the error amplification signal Vea is equal to or higher than the upper limit value Vref2 of the hysteresis comparison circuit, the voltage frequency converter is enabled to be used. An oscillating signal is generated such that the half bridge switching circuit switches according to the control signals (LVG and HVG). Conversely, when the error amplification signal Vea is lower than the lower limit value Vref1 of the hysteresis comparison circuit, the voltage converter is disabled to stop the generated oscillation signal, so that the half bridge switching circuit has no driving signal.

However, intermittent mode of operation control still has some deficiencies. For example, since the error amplification signal Vea will be on the hysteresis comparison circuit, The lower limit value Vref2 and Vref1 fluctuate, and the error amplification signal Vea is inversely proportional to the frequency fosc of the oscillating signal, so in a single Burst Mode Working Period (BMWP), the frequency fosc of the oscillating signal will follow The error amplification signal Vea changes from high to low and from low to high. In addition, in the first few driving pulse periods in the single intermittent mode duty cycle BMWP, a large resonant current (meaning that the resonant current is unbalanced) is generated due to the reduced impedance of the resonant network, thereby causing a large output voltage. Corrugation, audio noise, and optimum operating point variation (magnetoresistance current magnetic bias and zero voltage switching).

Based on the above considerations, there is a need for an intermittent control method that reduces output voltage ripple and audio noise and improves efficiency, and a resonant converter to which the control method is applied.

In view of the above, the present invention provides a resonant converter including a square wave generator, a resonant circuit, an output rectifier circuit, and a controller. The square wave generator is for providing a square wave voltage, the resonant circuit is for resonating according to the square wave voltage, and the output rectifier circuit is for outputting an output voltage according to the resonance of the resonant circuit. The controller is configured to provide a control signal to drive the square wave generator in an intermittent mode duty cycle, wherein the control signal comprises at least a first pulse group and at least a second pulse group, and the first pulse group includes at least one first adjustment pulse And the second pulse group includes a complex drive pulse. The square wave generator is configured to pre-adjust a magnetizing inductor current and a resonant capacitor voltage of the resonant circuit according to the first adjusting pulse to make the harmonic When the oscillating converter is at the rising edge of each of the driving pulses in the second pulse group, the magnetizing inductor currents are substantially equal, and the resonant capacitor voltages are also substantially equal.

The present invention also provides another resonant converter including a square wave generator, a resonant circuit, an output rectifier circuit, and a controller. The square wave generator is configured to provide a square wave voltage, a resonant circuit for resonating according to a square wave voltage, and an output rectifier circuit for outputting an output voltage according to the resonance of the resonant circuit. The controller is configured to provide a control signal to drive the square wave generator in an intermittent mode, wherein the control signal comprises at least a first pulse group and at least two second pulse groups, and the first pulse group is located in the two second pulse groups Between and including at least one first adjustment pulse, and the second pulse group is located after the first adjustment pulse and includes a plurality of drive pulses. The square wave generator is configured to adjust a magnetizing inductor current and a resonant capacitor voltage according to the first adjusting pulse so that the resonant converter has a magnetizing inductor current at a rising edge of each of the driving pulses in the second pulse group They are roughly equal, and the resonant capacitor voltages are also roughly equal.

The present invention also provides an intermittent mode control method for a resonant converter, comprising: providing at least one first adjustment pulse for pre-adjusting a magnetizing inductor current and a resonant capacitor voltage of a resonant circuit in an intermittent mode duty cycle And after the first adjustment pulse, providing at least one pulse sequence for intermittently turning on the plurality of switching elements in the square wave generator. The pulse sequence includes a complex drive pulse, and the first adjustment pulse is used to adjust the magnetizing inductor current of the resonant circuit and the resonant capacitor voltage such that the resonant inductor current is substantially greater when the resonant converter rises at the rising edge of each of the pulse trains Equal, and the resonant capacitor voltages are also roughly equal.

The above described objects, features and advantages of the present invention will become more apparent from the description of the appended claims.

The present invention provides a resonant converter that pre-adjusts the magnetizing inductor current and the resonant capacitor voltage of the resonant circuit to reduce output voltage ripple and audible noise and improve efficiency.

Figure 2 is a circuit diagram of one of the resonant converters of the present invention. As shown, the resonant converter 100 includes a main circuit 110 and a controller 120. The main circuit 110 includes a square wave generator 111, a resonant circuit 113, and an output rectifying circuit 115. The square wave generator 111 is for supplying a square wave voltage to the resonance circuit 113. In this embodiment, the square wave generator 111 can be a half bridge converter, a full bridge converter, a push-pull converter, but is not limited thereto, and the square wave generator 111 can also be another type of conversion. Device. For example, the square wave generator 111 is configured to receive an input voltage Vin, convert the input voltage Vin into a square wave voltage according to the control signal 117 generated by the controller 120, and provide the square wave voltage to the resonant circuit 113. . In general, the control signal 117 generated by the controller 120 is comprised of a plurality of pulses.

The resonant circuit 113 can be formed by a resonant component (such as an inductor and a capacitor) for receiving a square wave voltage from the square wave generator 111 for resonance, and the output rectifier circuit 115 is coupled to the resonant circuit 113 for the resonant circuit 113 according to the resonant circuit 113. The resonance produces an output voltage Vo. For example, the output rectifier circuit 115 can be a diode rectifier circuit or a synchronous rectifier circuit, but is not limited. It is here. The controller 120 includes a normal mode controller 121, an intermittent mode controller 123, and a driver 125. The controller 120 is configured to determine an operation mode of the resonant converter 100 according to a signal (for example, an output voltage error amplification signal) of the resonant converter 100 for reflecting an output current, and provide a corresponding control signal 117 to the square wave generator 111. In some embodiments, the signal used to reflect the output current in the resonant converter 100 may also be a voltage on the resonant capacitor (also referred to as a resonant capacitor voltage), a current in the high frequency transformer (eg, a magnetizing inductor current or a resonant current). One or more of them, but is not limited thereto. For example, the driver 125 selectively generates a control signal 117 output to the square wave generator 111 according to the oscillation signal provided by the normal mode controller 121 and the intermittent mode controller 123.

When the resonant converter 100 is under full load or heavy load, the intermittent mode controller 123 will be disabled and the normal mode controller 121 will be enabled. At this time, the normal mode controller 121 generates an oscillating signal according to the fluctuation of the output voltage Vo, and the driver 125 issues a control signal 117 having a continuous driving pulse to the square wave generation according to the oscillating signal generated by the normal mode controller 121. 111. In other words, the resonant converter 100 is now operating in a normal (operating) mode.

When the resonant converter 100 enters a light or no load condition, the normal mode controller 121 is disabled and the intermittent mode controller 123 is enabled, meaning to enter an intermittent (operating) mode. At this time, the driver 125 sends a control signal 117 having at least a first pulse group and at least a second pulse group to the square wave generator 111 according to the oscillation signal provided by the intermittent mode controller 123. For example, the second pulse group includes a pulse sequence including a plurality of drive pulses for intermittently turning on the opening in the square wave generator 111. The component is turned off, but is not limited to this. It is to be noted that the first pulse group is located before the second pulse group or between two adjacent second pulse groups, but is not limited thereto. For example, the driver 125 can sequentially provide the first pulse group and the second pulse group to the square wave generator 111. The square wave generator 111 is configured to pre-adjust the magnetizing inductor current and the resonant capacitor voltage of the resonant circuit 113 to corresponding preset values according to the first pulse group, so that the resonant circuit of the rising edge of each pulse in the second pulse group In 113, the magnetizing inductor currents will be roughly equal, and the resonant capacitor voltages will be roughly equal. In other words, the driver 125 causes the resonant converter 100 to operate in a certain equilibrium state of the normal (operating) mode in accordance with the second set of pulses. It should be noted that the resonant converter 100 has a plurality of balanced operating states in the normal mode, and the balanced operating state is related to the load. Further, unlike the conventional technique shown in Fig. 1, the second pulse group is generated by the driver 125 by the intermittent mode controller 123 based on the oscillation signal of the fixed frequency. In other words, even if the error amplification signal generated based on the output voltage Vo fluctuates between the lower limit value and the lower limit value, there is no influence on the second pulse group.

In an embodiment, the first pulse group includes one or more first adjustment pulses, and the width and number of the first adjustment pulses are determined according to the number of resonant elements in the resonant circuit 113, but are not limited. herein. In some embodiments, the first pulse group includes one or more first adjustment pulses and one or more second adjustment pulses, and the width and number of the first and second adjustment pulses are also in accordance with the resonance circuit 113. The number of resonant elements is determined, but is not limited thereto. In some embodiments, the widths of the first and second adjustment pulses are calculated from equations. In some embodiments, the widths of the first and second adjustment pulses are detectable by detecting the excitation current of the resonant circuit The one of the sense current, the resonant current, and the resonant capacitor voltage is adjusted instantaneously, but is not limited thereto.

Since the first pulse group has previously adjusted the magnetizing inductor current and the resonant capacitor voltage of the resonant circuit to a preset value, it is possible to avoid generating a large resonant current in the first few driving pulse periods in the second pulse group. Therefore, the large output voltage ripple, audio noise, and optimum operating point variation (magnetoresistance current magnetic bias and zero voltage switching) can be overcome by the resonance current imbalance.

Figure 3 is an embodiment of a resonant converter of the present invention. As shown, the resonant converter 200 includes a main circuit 210 and a controller 220. The main circuit 210 includes an input capacitor 211, a half bridge converter 212, a resonant circuit 213, a high frequency transformer 214, and an output rectification. Circuit 215 and an output capacitor 216. In this embodiment, the input capacitor 211 is configured to receive and store the input voltage Vin, and the half bridge converter 212 is used as a square wave generator for converting the input voltage Vin into a control signal 217 provided by the controller 220. The square wave voltage is supplied to the resonance circuit 213. In this embodiment, the half bridge converter 212 is constituted by the switching elements SW1 and SW2, but is not limited thereto. For example, the half bridge converter 212 can also be constructed of an insulated gate bipolar transistor (IGBT), an electromechanical switch, a micromechanical switch, or other active semiconductor switch connected in parallel with the diode. The high frequency transformer 214, the output rectifying circuit 215, and the output capacitor 216 are used as an output rectifying circuit to provide an output voltage Vo. In this embodiment, the output rectifying circuit 215 is composed of the diodes DSR1 and DSR2, but is not limited thereto, and may be composed of other rectifying elements, such as a synchronous rectifying tube.

The controller 220 includes a half bridge driver 221, a selection switch 222, a normal mode controller 223, an intermittent mode controller 224, a clock oscillator 225, a hysteresis comparison circuit 226, and a current detecting resistor 227. The controller 220 is configured to determine the operating mode of the resonant converter 200 according to the output voltage Vo, and provide a corresponding control signal 217 to the half bridge converter 212. The normal mode controller 223 is composed of a voltage frequency conversion circuit 2231 and a feedback error amplifying circuit 2232. For example, the feedback error amplifying circuit 2232 is configured to generate an error amplification signal Vea according to a voltage difference between the output voltage Vo and a predetermined voltage, and the voltage frequency conversion circuit 2231 outputs a corresponding oscillation signal according to the error amplification signal Vea. .

In the case of full load or heavy load, the intermittent mode controller 224 is disabled based on the output voltage Vo on the output capacitor 216, and the normal mode controller 223 is enabled to emit a continuous oscillating signal. At the same time, since the voltage on the current detecting resistor 227 is equal to or higher than the upper limit value of the hysteresis comparison circuit 226, the output signal 228 of the hysteresis comparison circuit 226 controls the selection switch 222 to generate the normal mode controller 223. The oscillation signal is output to the half bridge driver 221. Therefore, the half bridge driver outputs a control signal 217 to drive the half bridge converter 212 in accordance with the oscillation signal generated by the normal mode controller 223, so that the main circuit 210 of the resonant converter 200 operates in the normal mode. The operation of the main circuit 210 of the resonant converter 200 in the normal mode is the same as that of the prior art, and therefore will not be described herein.

In some embodiments, the hysteresis comparison circuit 226 can also be based on a voltage Vcr (also referred to as a resonant capacitor voltage) on the resonant capacitor Cr, a current in the high frequency transformer 214 (eg, a magnetizing inductor current or a resonant current), and feedback. One or more of the error amplification signals Vea generated by the error amplifying circuit 2232 controls the selection switch 222, but is not limited thereto. The resonant converter 100 has a plurality of balanced operating states in the normal mode, and the balanced operating state is related to the load. As shown in FIG. 4, in a certain equilibrium state in the normal mode, the magnetizing inductor current I _{LM of the} resonant circuit 213 has a positive peak Immax and a negative peak Immin, and the resonant capacitor voltage Vcr of the resonant circuit 213 is in the exciting inductance. When the current I _LM is a positive peak Immax and a negative peak Immin, respectively, there is a corresponding first voltage value Vcrmax and a second voltage value Vcrmin.

In the case of light load or no load, the normal mode controller 223 is disabled according to the output voltage Vo on the output capacitor, and the intermittent mode controller 224 is enabled for output according to the clock oscillator 225. A clock having a preset frequency produces a corresponding oscillating signal. At the same time, since the voltage on the current detecting resistor 227 is equal to or lower than the lower limit value of the hysteresis comparison circuit 226, the output signal 228 of the hysteresis comparison circuit 226 controls the selection switch 222 to generate the intermittent mode controller 224. The oscillation signal is output to the half bridge driver 221. Therefore, the half bridge driver 221 drives the half bridge converter 212 according to the oscillation signal output control signal 217 generated by the intermittent mode controller 224, so that the main circuit 210 of the resonant converter 200 operates in the intermittent mode.

In this embodiment, the control signal 217 output by the half bridge driver 221 according to the oscillation signal generated by the intermittent mode controller 224 includes at least a first pulse group and at least a second pulse group for controlling the half bridge converter. Switching elements SW1 and SW2 in 212. Fig. 4 is a schematic diagram showing the operation waveform of the main circuit of the resonant converter in the intermittent mode. As shown, Vgss2 is the drive signal of the switching element SW2 of the half bridge converter 212, Vgss1 is the drive signal of the switching element SW1 of the half bridge converter 212, and I _LM is the exciting inductance Lm of the resonant circuit 213. magnetizing inductor current on, Ir-based resonant circuit 213, resonant current (the current in resonant inductor), Vcr for the resonant capacitor voltage of the resonant circuit 213 of, I _SR is output rectifying circuits 215 diode DSR1 and DSR2 conduction Current.

It should be noted that, in this embodiment, the control signal 217 is composed of the drive signals Vgss2 and Vgss1, and the control signal 217 has a first adjustment pulse Δt1 at times t0 to t1, and has a first time at time t2 to t3. The second adjustment pulse Δt2, the first and second adjustment pulses Δt1 and Δt2 can be regarded as the aforementioned first pulse group, and the pulse sequence formed by the plurality of drive pulses between the times t1 and t2 in the control signal 217 It can be regarded as the aforementioned second pulse group, but is not limited thereto. The square wave generator 212 is connected to the switching element SW1 of the half bridge converter 212 according to the first adjustment pulse Δt1 at time t0 to t1, and the resonant capacitor voltage Vcr and the magnetizing inductor current I _LM are respectively advanced from the intermediate values Vcrmid and 0. The first voltage value Vcrmax and the positive peak Immax are adjusted. Then, during the time t1 to t2, the square wave generator 212 sequentially turns on the switching elements SW2 and SW1 according to the driving pulse in the second pulse group of the control signal 217 (that is, the switching elements SW1 and SW2 are turned on intermittently). ). Furthermore, at time t2 to t3, the square wave generator 212 turns on the switching element SW1 according to the second adjustment pulse Δt2, and adjusts the resonant capacitor voltage Vcr and the exciting inductor current I _LM to the intermediate values Vcrmid and 0, respectively.

The first adjustment pulse is used to pre-adjust the resonant capacitor voltage Vcr and the magnetizing inductor current I _LM at time t0 to t1 such that the resonant circuit reaches a balanced resonant operating state (also referred to as an equilibrium state) at time t1. In this embodiment, the so-called balanced resonant operating state means that the resonant capacitor voltage Vcr and the exciting inductor current I _{LM are} balanced, and the resonant capacitor voltage Vcr and the exciting inductor current I _LM are the same as in the normal operating mode while maintaining resonance. The zero-voltage switching characteristics of the converter. In other words, at time t1 to t2, when the rising edge of each of the driving pulses in the control signals 217 of the switching elements SW1 and SW2, the inductor current I _LM in the resonant circuit 213 is substantially equal, and the resonant capacitor voltage Vcr is also substantially equal.

In the present embodiment, the pulse widths of the first and second adjustment pulses Δt1 and Δt2 are calculated by the following equations.

Vcr ( t 0)=( nVo + Vcr max- Vin )×cos( ω 0×Δ t 2)− Lr × ω 0×Im max×sin( ω 0×Δ t 2)+ Vin - nVo

among them Cr represents the value of the resonant capacitor, Lr represents the value of the resonant inductor, Lm represents the value of the magnetizing inductance, Vin represents the input voltage, n represents the turns ratio of one of the high-frequency transformers 214, and the secondary side, and Immax represents the positive of the magnetizing inductor current I _LM The peak value, Vcrmax represents the voltage value on the resonant capacitor Cr corresponding to the positive inductor current I _LM is the positive peak in the normal operating mode, and Vcrmin represents the voltage on the resonant capacitor Cr corresponding to the magnetizing inductor current I _LM in the normal operating mode. The value ω1 is the oscillation angular frequency of the resonance circuit 213 when the first driving pulse (first adjustment pulse) acts, and ω0 is the oscillation angular frequency of the resonance circuit 213 when the last driving pulse (second adjustment pulse) acts, and Vcr( T0) is the voltage across the resonant capacitor Cr at time t0.

In this embodiment, since the frequency of the oscillation signal supplied from the intermittent mode controller 224 does not change with the fluctuation of the error amplification signal Vea at times t1 to t2, and the first pulse group has the magnetizing inductance of the resonance circuit 213 The current I _LM and the resonant capacitor voltage Vcr are previously adjusted to preset values, so that it is possible to effectively avoid generating a large resonant current in the first few driving pulse periods in the second pulse group. In addition, since the resonant converter 200 operates in a balanced operating state throughout the duty cycle, it can meet the requirements of output voltage ripple, audio noise, and light load high efficiency.

In an embodiment, since the first and second adjustment pulses Δt1 and Δt2 are configured, the resonant current spike in the first few driving pulse periods of the second pulse group is less than 1.8 times the balanced resonant operating state. The resonant current Ir is used to meet the general requirements of low output voltage ripple and audible noise. In another embodiment, the first and second adjustment pulses Δt1 and Δt2 are configured according to the foregoing equation, and the resonance current spikes in the first few driving pulse periods of the second pulse group are less than 1.4 times the equilibrium resonance. The resonant current Ir in the working state is used to meet the high requirements of low output voltage ripple and audible noise. In a preferred embodiment, the first and second adjustment pulses Δt1 and Δt2 are further fine-tuned such that the resonant current spikes in the first few drive pulse periods of the second pulse group are less than 1.2 times the balanced resonant operation state. The resonant current Ir is used to meet the higher requirements of low output voltage ripple and audible noise. In the embodiment of FIG. 4, the intermediate value Vcrmid of the resonant capacitor voltage Vcr is between the first voltage value Vcrmax and the second voltage value Vcrmin, but in some embodiments, the intermediate value Vcrmid of the resonant capacitor voltage Vcr may also be It is higher than the first voltage value Vcrmax or lower than the second voltage value Vcrmin.

Figure 5 is an implementation of the intermittent mode of operation. As shown, the intermittent mode controller 224 includes a drive pulse synchronization circuit 311, a preset Pulse width circuit 312, a sum gate 313, dead band circuits 314 and 315, and inverter 316. The clock oscillator 225 is used to generate an oscillating signal having a preset fixed frequency, and the hysteresis comparison circuit 226 is used to set a threshold value of the error amplifying signal. The driving pulse synchronization circuit 311 is configured to synchronize the output signal of the hysteresis comparison circuit 226 with the driving pulse, and the preset pulse width circuit 312 is configured to set the first pulse of the single resonance period by the RC delay (first adjustment) Pulse) and the width of the last pulse (second adjustment pulse). The gate 313 is used to control the state of the driving pulse, and the dead zone circuits 314 and 315 are used to generate the dead time of the switching of the switching elements SW1 and SW2.

Figure 6 is another embodiment of a resonant converter. As shown, the resonant converter 300 is similar to the resonant converter 200 of FIG. 4, with the difference that the pulse widths of the first and second adjustment pulses Δt1 and Δt2 in the control signal 217 are not calculated by the aforementioned equation. However, it is adjusted in time by detecting the magnetizing inductor current and the resonant capacitor voltage converter in the resonant circuit 213. To simplify the description, the same components of the resonant converter 300 as the resonant converter 200 of FIG. 4 and their actions are not described herein. As shown, the controller 220" includes an inductor Ld as a magnetizing inductor current monitoring component to monitor the magnetizing inductor current I _{LM of the} resonant circuit 213 and to feed the measured magnetizing inductor current I _{LM to the} intermittent mode controller 224" . In addition, the controller 220" also monitors the resonant capacitor voltage Vcr of the resonant circuit 213 and sends the measured resonant capacitor voltage Vcr to the intermittent mode controller 224". The intermittent mode controller 224" instantaneously controls the pulse widths of the first and second adjustment pulses based on the measured resonant capacitor voltage Vcr and the magnetizing inductor current I _LM such that each of the second pulse groups of the control signal 217 When the rising edge of the driving pulse comes, the exciting inductor current I _LM in the resonant circuit 213 is substantially equal, and the resonant capacitor voltage Vcr is also substantially equal.

For example, in the case of light or no load, the normal mode controller 223 is disabled based on the output voltage Vo on the output capacitor, and the intermittent mode controller 224" is enabled to generate the corresponding pulse. At the same time, since the voltage on the current detecting resistor 227 is lower than the lower limit value of the hysteresis comparison circuit 226, the output signal 228 of the hysteresis comparison circuit 226 controls the selection switch 222 to generate the intermittent mode controller 224". The oscillation signal is output to the half bridge driver 221. Therefore, the half bridge driver 221 outputs the control signal 217 to drive the half bridge converter 212 according to the oscillation signal generated by the intermittent mode controller 224", so that the main circuit 210 of the resonant converter 200 operates in the intermittent mode.

In the intermittent mode, the control signal 217 output by the half bridge driver 221 according to the oscillation signal generated by the intermittent mode controller 224 includes at least one first pulse group (for example, the first and second adjustment pulses Δt1 in FIG. 4 and Δt2) and at least one second pulse group (for example, the complex drive pulses of times t1 to t2 in FIG. 4) for controlling the switching elements SW1 and SW2 in the half bridge converter 212. Before the second pulse group, the half bridge driver 221 outputs a first adjustment pulse Δt1 according to the oscillation signal generated by the intermittent mode controller 220", so that the square wave generator 212 turns on the switching element SW1 according to the first adjustment pulse Δt1. For pre-adjusting the resonant capacitor voltage Vcr and the magnetizing inductor current I _LM from the intermediate value Vcrmid and 0 to the first voltage value Vcrmax and the positive peak Immax, respectively, in order to bring the resonant circuit 213 to a balanced resonant operating state. The pulse width of the first adjustment pulse Δt1 is determined by the time required for the resonance capacitor voltage Vcr and the magnetizing inductor current I _{LM to be} adjusted to the first voltage value Vcrmax and the positive peak Immax. After the resonant capacitor voltage Vcr and the magnetizing inductor current I _LM have been adjusted to the first voltage value Vcrmax and the positive peak Immax, the first adjusting pulse Δt1 is ended.

Next, the half bridge driver 221 outputs a second pulse group according to the oscillation signal generated by the intermittent mode controller 220", and the square wave generator 212 sequentially turns on the switching element SW2 according to the second pulse group in the control signal 217. SW1. Further, after the end of the second pulse group, the half bridge driver 221 outputs a second adjustment pulse Δt2 according to the oscillation signal generated by the intermittent mode controller 220", so that the square wave generator 212 is adjusted according to the second The pulse Δt2 turns on the switching element SW1 for pre-adjusting the resonant capacitor voltage Vcr and the exciting inductor current I _LM to the intermediate values Vcrmid and 0, respectively. In this embodiment, the pulse width of the second adjustment pulse Δt2 is determined by the time required for the resonance capacitor voltage Vcr to be adjusted to the intermediate Vcrmid. After the intermittent mode controller determines that the resonant capacitor voltage Vcr has been adjusted to the intermediate value Vcrmid, the second adjustment pulse Δt2 is ended. In some embodiments, the second adjustment pulse Δt2 can be omitted, and the first adjustment pulse Δt2 can also be adjusted to the first voltage value Vcrmax or the excitation inductor current I _LM to the positive peak value by the resonance capacitor voltage Vcr. The time required for Immax is determined.

Similarly, since the first pulse group has previously adjusted the magnetizing inductor current I _LM and the resonant capacitor voltage Vcr of the resonant circuit 213 to a preset value, the first few driving pulse periods in the second pulse group can be effectively avoided. Produces a large resonant current. In addition, since the resonant converter 300 operates in a balanced operating state throughout the duty cycle, it can meet the requirements of output voltage ripple, audible noise, and light load high efficiency.

Figure 7 is a schematic diagram of the operational waveform of the resonant converter operating in the intermittent mode. As shown, the control signal includes a first pulse group (Δt1 and Δt2) and a second pulse group (PS2) in each intermittent mode duty cycle BMWP. In this embodiment, the second pulse group PS2 is a pulse sequence having a plurality of drive pulses, and the first pulse group is connected to the second pulse group by the first adjustment pulse Δt1 located before the second pulse group PS2. The second adjustment pulse Δt2 after PS2 is formed, but is not limited thereto. The second adjustment pulse Δt2 is used to adjust the resonant capacitor voltage Vcr to the intermediate value Vcrmid after the end of the previous second pulse group PS2, and the first adjustment pulse Δt1 is used before the start of the next second pulse group PS2. The resonant capacitor voltage Vcr and the magnetizing inductor current I _LM are respectively adjusted from the intermediate value Vcrmid and 0 to the first voltage value Vcrmax and the positive peak Immax. Since the magnetizing inductor current I _LM and the resonant capacitor voltage Vcr of the resonant circuit have been adjusted to the first voltage value Vcrmax and the positive peak Immax, it is effectively avoided that the first few driving pulse periods in the second pulse group PS2 are generated very much. The large resonant current allows the resonant converter to operate in a balanced operating state. Therefore, when the rising edge of each driving pulse in the second pulse group PS2, the inductor current I _LM is substantially equal, and the resonant capacitor voltage Vcr is also substantially equal. It is to be noted that the pulse widths of the first and second adjustment pulses may be pre-calculated according to the equation, or may be adjusted instantaneously by detecting the magnetizing inductor current I _LM and the resonant capacitor voltage Vcr, but are not limited thereto. In some embodiments, the control signal may also omit the second adjustment pulse Δt2 in each intermittent mode duty cycle BMWP, and includes only a first pulse group (Δt1) and a second pulse group (PS2). .

Figure 8 is a schematic diagram of another operational waveform when the resonant converter is operating in the intermittent mode. As shown, the control signal includes a first pulse group PS1 (Δt1 and Δt2) and a second pulse group (PS2) in each intermittent mode duty cycle BMWP. In this embodiment, the second pulse group PS2 is a pulse sequence having a plurality of drive pulses, and the first pulse group PS1 is composed of a first adjustment pulse Δt1 and a second adjustment pulse Δ located before the second pulse group PS2. It is composed of t2, but is not limited thereto. Before the start of the second second pulse group PS2, the second adjustment pulse Δt2 is used to adjust the resonance capacitance voltage Vcr to the intermediate value Vcrmid, and the first adjustment pulse Δt1 then respectively resonates the capacitance voltage Vcr and the excitation inductance current I _LM The intermediate value Vcrmid and 0 are adjusted to the first voltage value Vcrmax and the positive peak Immax, so that the inductor current I _LM is substantially equal to the rising edge of each driving pulse in the second pulse group PS2, and the resonant capacitor voltage Vcr is also large. The above will be equal. Similarly, the pulse widths of the first and second adjustment pulses may be calculated in advance according to an equation, or may be instantaneously adjusted by detecting the magnetizing inductor current I _LM and the resonant capacitor voltage Vcr, but are not limited thereto. In some embodiments, the first pulse group PS1 of the control signal in each intermittent mode duty cycle BMWP may also omit the second adjustment pulse Δt2 and include only a first adjustment pulse Δt2.

Figure 9 is a schematic diagram of another operational waveform when the resonant converter is operating in the intermittent mode. As shown, the control signal includes a first pulse group (Δt1_1, Δt1_2, Δt2_1, and Δt2_2) and a second pulse group (PS2) in each intermittent mode duty cycle BMWP. In this embodiment, the second pulse group PS2 is a pulse sequence having a plurality of drive pulses, and the first pulse group is composed of the first adjustment pulses Δt1_1 and Δt1_2 located before the second pulse group PS2 and The second adjustment pulses Δt2_1 and Δt2_2 after the second pulse group PS2 are formed, but are not limited thereto. For example, the first adjustment pulse The rushes Δt1_1 and Δt1_2 can be regarded as one pulse sequence, and the second adjustment pulses Δt2_1 and Δt2_2 can be regarded as another pulse sequence.

The second adjustment pulses Δt2_1 and Δt2_2 are used to adjust the resonant capacitor voltage Vcr to the intermediate value Vcrmid after the end of the previous second pulse group PS2, and the first adjustment pulses Δt1_1 and Δt1_2 are used in the second Before the start of the pulse group PS2, the resonant capacitor voltage Vcr and the magnetizing inductor current I _LM are respectively adjusted from the intermediate value Vcrmid and 0 to the first voltage value Vcrmax and the positive peak Immax. Since the magnetizing inductor current I _LM and the resonant capacitor voltage Vcr of the resonant circuit have been adjusted to the first voltage value Vcrmax and the positive peak Immax, it is effectively avoided that the first few driving pulse periods in the second pulse group PS2 are generated very much. The large resonant current allows the resonant converter to operate in a balanced operating state. Therefore, in the rising edge of each driving pulse in the second pulse group PS2, the magnetizing inductor currents I _{LM are} substantially equal, and the resonant capacitor voltage Vcr is also substantially equal. It is to be noted that the pulse widths of the first and second adjustment pulses may be pre-calculated according to the equation, or may be adjusted instantaneously by detecting the magnetizing inductor current I _LM and the resonant capacitor voltage Vcr, but are not limited thereto. The number of the first adjustment pulses and the number of the second adjustment pulses in the first pulse group are determined according to the number of resonance elements in the resonance circuit, but are not limited thereto. In an embodiment, more first adjustment pulses and second adjustment pulses may be included in the first pulse group. In some embodiments, the control signal may also omit the second adjustment pulses Δt2_1 and Δt2_2 in each intermittent mode duty cycle BMWP, but only include the first pulse group (Δt1_1 and Δt1_2) and the second pulse. Group (PS2).

While the present invention has been described above in terms of the preferred embodiments thereof, it is not intended to limit the invention, and the invention may be modified and modified without departing from the spirit and scope of the invention. range This is subject to the definition of the scope of the patent application.

100, 200, 300‧‧‧ resonant converter

110, 210‧‧‧ main circuit

120, 220, 220" ‧ ‧ controller

111‧‧‧ square wave generator

113, 213‧‧‧ resonant circuit

115, 215‧‧‧ output rectifier circuit

117, LVG, HVG, 217‧‧‧ control signals

121, 223‧‧‧ normal mode controller

123, 224, 224” ‧‧‧ intermittent mode controller

125‧‧‧ drive

211‧‧‧ input capacitor

212‧‧‧Half-bridge converter

214‧‧‧High frequency transformer

216‧‧‧ output capacitor

221‧‧‧ Half-Bridge Driver

222‧‧‧Selection switch

225‧‧‧clock oscillator

226‧‧‧ hysteresis comparison circuit

227‧‧‧current sense resistor

228‧‧‧Output signal

2231‧‧‧Voltage-frequency conversion circuit

2232‧‧‧Return error amplifier circuit

311‧‧‧Drive pulse synchronization circuit

312‧‧‧Preset pulse width circuit

313‧‧‧ and gate

314, 315‧‧‧ dead zone circuit

316‧‧‧Inverter

SW1, SW2‧‧‧ switching components

DSR1, DSR2‧‧‧ diode

Vin‧‧‧Input voltage

Vo‧‧‧ output voltage

Cr‧‧‧Resonance Capacitor

Vcr‧‧‧Resonant capacitor voltage

I _LM ‧‧‧Magnetic inductor current

Immax‧‧‧ is peaking

Immin‧‧‧negative peak

Vcrmax‧‧‧ first voltage value

Vcrmin‧‧‧second voltage value

Vcrmid‧‧‧ intermediate value

Vgss1, Vgss2‧‧‧ drive signals

Lm‧‧‧Magnetic Inductance

Ir‧‧‧Resonance current

I _SR ‧‧‧ on current

PS1‧‧‧First Pulse Group

PS2‧‧‧Second pulse group

Vea‧‧‧ error amplification signal

Vref1‧‧‧ lower limit

Vref2‧‧‧ upper limit

Fosc‧‧‧ frequency

Ld, Ls‧‧‧Inductors

BMWP‧‧‧ intermittent mode duty cycle

△t1, △t1_1, △t1_2‧‧‧ first adjustment pulse

△t2, △t2_1, △t2_2‧‧‧second adjustment pulse

Fig. 1 is a schematic diagram showing the operation waveform of a conventional resonant converter in an intermittent mode.

Figure 2 is a circuit diagram of one of the resonant converters of the present invention.

Figure 3 is an embodiment of a resonant converter of the present invention.

Fig. 4 is a schematic diagram showing the operation waveform of the main circuit of the resonant converter in the intermittent mode.

Figure 5 is an implementation of the intermittent mode of operation.

Figure 6 is another embodiment of a resonant converter.

Figure 7 is a schematic diagram of the operational waveform of the resonant converter operating in the intermittent mode.

Figure 8 is a schematic diagram of another operational waveform when the resonant converter is operating in the intermittent mode.

Figure 9 is a schematic diagram of another operational waveform when the resonant converter is operating in the intermittent mode.

100‧‧‧Resonance Converter

110‧‧‧ main circuit

120‧‧‧ Controller

111‧‧‧ square wave generator

113‧‧‧Resonance circuit

115‧‧‧Output rectifier circuit

Vin‧‧‧Input voltage

Vo‧‧‧ output voltage

121‧‧‧Normal mode controller

123‧‧‧Intermittent mode controller

125‧‧‧ drive

117‧‧‧Control signal

Claims (41)

A resonant converter for operating in a normal mode or a batch mode, the resonant converter comprising: a square wave generator for providing a square wave voltage; and a resonant circuit for resonating according to the square wave voltage; a controller for providing a control signal to drive the square wave generator in an intermittent mode operation period in which the resonant converter is operated in light or no load, wherein the control signal includes at least a first pulse group and at least a second pulse group, the first pulse group includes at least one first adjustment pulse, and the second pulse group includes a plurality of drive pulses, and the square wave generator is configured to apply to the resonant circuit according to the first adjustment pulse a magnetizing inductor current and a resonant capacitor voltage are pre-adjusted such that when the resonant converter is at a rising edge of each of the second pulse groups, the magnetizing inductor currents are substantially equal, and the resonant capacitor voltage is also substantially Equal on. The resonant converter of claim 1, wherein the pulse width of the first adjustment pulse is calculated by one of the programs. The resonant converter of claim 1, wherein the pulse width of the first adjustment pulse is instantaneously adjusted by detecting the magnetizing inductor current and the resonant capacitor voltage. The resonant converter of claim 1, wherein when the resonant converter is operated in an equilibrium state in the normal mode, the magnetizing inductor current has a positive peak and a negative peak, and the resonant capacitor The voltage has a first voltage value corresponding to one of the positive peaks, a second voltage value corresponding to one of the negative peaks, and an intermediate value. The resonant converter according to claim 4, wherein the square wave generator pre-adjusts the magnetizing inductor current and the resonant capacitor voltage to the positive peak value and the first voltage value, respectively, according to the first adjusting pulse. . The resonant converter of claim 4, wherein the second pulse group is coupled to the first adjustment pulse, and the first pulse group further comprises at least one second adjustment pulse connected to the second pulse After the group, the square wave generator is configured to adjust the resonant capacitor voltage of the resonant circuit according to the second adjusting pulse. The resonant converter of claim 4, wherein the first pulse group further comprises at least one second adjustment pulse, the first adjustment pulse is connected after the second adjustment pulse, and the second pulse group is After the first adjustment pulse is connected, the square wave generator adjusts the resonant capacitor voltage of the resonant circuit according to the second adjustment pulse. The resonant converter according to claim 7, wherein the square wave generator pre-adjusts the resonant capacitor voltage to the intermediate value according to the second adjusting pulse. The resonant converter of claim 4, wherein a pulse width of the first adjustment pulse is adjusted by the resonant capacitor voltage and the magnetizing inductor current to a time required for the first voltage value and the positive peak value decided. The resonant converter of claim 4, wherein the first pulse group includes a plurality of first adjustment pulses, and the second pulse group is coupled to the first adjustment pulse to cause the square wave generator The magnetizing inductor current and the resonant capacitor voltage are respectively adjusted to the positive peak value and the first voltage value, respectively. The resonant converter of claim 10, wherein the first pulse group further comprises a plurality of second adjustment pulses connected to the second pulse group, such that the square wave generator adjusts the resonant capacitor voltage to the above Median. The resonant converter of claim 10, wherein the number of the first adjustment pulses is determined according to the number of resonant elements in the resonant circuit. A resonant converter for operating in a normal mode or an intermittent mode, the resonant converter comprising: a square wave generator for providing a square wave voltage; and a resonant circuit for resonating according to the square wave voltage; And a controller for providing the control signal to drive the square wave generator in the intermittent mode in which the resonant converter is operated in light or no load, wherein the control signal comprises at least a first pulse group and at least two a second pulse group, wherein the first pulse group is located between the two second pulse groups, and includes at least one first adjustment pulse, and includes a plurality of driving pulses, wherein the square wave generator is used according to the first Adjusting a pulse, adjusting a magnetizing inductor current and a resonant capacitor voltage of the resonant circuit such that when the resonant converter is at a rising edge of each of the second pulse groups, the magnetizing inductor currents are substantially equal, and The resonant capacitor voltages are also roughly equal. A resonant converter as claimed in claim 13 wherein When the resonant converter operates in an equilibrium state in the normal mode, the magnetizing inductor current has a positive peak and a negative peak, and the resonant capacitor voltage has a first voltage value corresponding to one of the positive peaks, corresponding to a second voltage value of one of the above negative peaks, and an intermediate value. The resonant converter according to claim 14, wherein the square wave generator adjusts the magnetizing inductor current and the resonant capacitor voltage to the positive peak value and the first voltage value, respectively, according to the first adjusting pulse. The resonant converter of claim 14, wherein the first pulse group further comprises at least one second adjustment pulse connected to the second pulse group, such that the square wave generator converts the resonance of the resonant circuit The capacitor voltage is adjusted to the above intermediate value. The resonant converter of claim 14, wherein the first pulse group further comprises at least one second adjustment pulse, the first adjustment pulse is connected after the second adjustment pulse, and the square wave generator is The second adjustment pulse adjusts the resonant capacitor voltage of the resonant circuit to the intermediate value. The resonant converter of claim 14, wherein the number of the first adjustment pulses is determined according to the number of resonant elements in the resonant circuit. The resonant converter of claim 14, wherein the pulse width of the first adjustment pulse is calculated by one of the programs. The resonant converter of claim 14, wherein the pulse width of the first adjustment pulse is instantaneously adjusted by detecting the magnetizing inductor current and the resonant capacitor voltage. An intermittent mode control method for a resonant converter, wherein the resonant converter is configured to operate in a normal mode or an intermittent mode, and in the intermittent mode, the resonant converter operates at light or no load, and the resonant converter is intermittent The mode control method includes: providing at least one first adjustment pulse for pre-adjusting a magnetizing inductor current and a resonant capacitor voltage of one of the resonant circuits in one of the intermittent mode working cycles; After adjusting the pulse, providing at least one pulse sequence for intermittently turning on the plurality of switching elements in the square wave generator, wherein the pulse sequence comprises a plurality of driving pulses, and the first adjusting pulse is used to adjust the resonant circuit The magnetizing inductor current and the resonant capacitor voltage are such that when the resonant converter rises at a rising edge of each of the pulse trains, the magnetizing inductor currents are substantially equal, and the resonant capacitor voltages are substantially equal. The intermittent mode control method of the resonant converter according to claim 21, wherein when the resonant converter operates in an equilibrium state in the normal mode, the magnetizing inductor current has a positive peak and a negative peak. And the resonant capacitor voltage has a first voltage value corresponding to one of the positive peaks, a second voltage value corresponding to one of the negative peaks, and an intermediate value. The intermittent mode control method of the resonant converter according to claim 22, wherein the first adjusting pulse is configured to adjust the magnetizing inductor current and the resonant capacitor voltage to the positive peak value and the first voltage value, respectively. . Intermittent of the resonant converter as described in claim 22 The mode control method further includes: providing at least one second adjustment pulse connected to the pulse sequence to adjust the resonant capacitor voltage of the resonant circuit to the intermediate value, wherein the intermediate value is located at the first and second voltage values between. The intermittent mode control method of the resonant converter of claim 22, further comprising: before the first adjusting pulse, providing at least one second adjusting pulse for adjusting the resonant capacitor voltage of the resonant circuit to The above intermediate value. The intermittent mode control method of the resonant converter according to claim 21, wherein the number of the first adjustment pulses is determined according to the number of resonant elements in the resonant circuit. The intermittent mode control method of the resonant converter according to claim 21, wherein the pulse width of the first adjustment pulse is calculated by one of the programs. The intermittent mode control method of the resonant converter according to claim 21, wherein the pulse width of the first adjustment pulse is instantaneously adjusted by detecting the magnetizing inductor current and the resonant capacitor voltage. A controller for a resonant converter for operating in a normal mode or an intermittent mode, wherein a controller of the resonant converter is configured to operate in a batch mode of light or no load on behalf of the resonant converter a control signal is provided in the working cycle, the control signal includes at least a first pulse group and at least a second pulse group, the first pulse group includes at least one first adjustment pulse, and the second pulse group includes a plurality of driving pulses. The first adjustment pulse is used to pre-adjust a resonance of a resonant circuit The magnetic inductor current and a resonant capacitor voltage are such that when the resonant converter is at the rising edge of each of the second pulse groups, the magnetizing inductor currents are substantially equal, and the resonant capacitor voltages are also substantially equal. A controller for a resonant converter according to claim 29, wherein a pulse width of said first adjustment pulse is instantaneously adjusted by detecting said magnetizing inductor current and said resonant capacitor voltage. The controller for a resonant converter according to claim 29, wherein when the resonant converter is operated in the normal state of the normal mode, the magnetizing inductor current has a positive peak and a negative peak. The resonant capacitor voltage has a first voltage value corresponding to the positive peak, a second voltage value corresponding to the negative peak, and an intermediate value. The controller for a resonant converter according to claim 31, wherein the first adjusting pulse is used to pre-adjust the magnetizing inductor current and the resonant capacitor voltage to the positive peak value and the first voltage value, respectively. . The controller for a resonant converter according to claim 31, wherein the second pulse group is connected after the first adjustment pulse, and the first pulse group further comprises at least one second adjustment pulse connected After the second pulse group, the resonant capacitor voltage of the resonant circuit is adjusted. The controller for a resonant converter according to claim 31, wherein the first pulse group further includes at least one second adjustment pulse, the first adjustment pulse being connected to the second adjustment pulse, and The second pulse group is connected to the first adjustment pulse, and the second adjustment pulse is used to adjust the resonance capacitor voltage of the resonance circuit to the intermediate value in advance. The controller for a resonant converter according to claim 31, wherein a pulse width of said first adjustment pulse is adjusted by said resonant capacitor voltage and said magnetizing inductor current to said first voltage value and said positive peak value The time required is determined. A controller for a resonant converter for operating in a normal mode or an intermittent mode, wherein a controller of the resonant converter is configured to operate in a batch mode of light or no load on behalf of the resonant converter Providing a control signal in the working cycle, the control signal comprising at least one first pulse group and at least two second pulse groups, the first pulse group being located between the two second pulse groups, and including at least one first adjustment a pulse, the second pulse group includes a plurality of driving pulses, wherein the first adjusting pulse is used to adjust a magnetizing inductor current and a resonant capacitor voltage of a resonant circuit, so that each of the resonant converters in each of the second pulse groups is driven At the rising edge of the pulse, the magnetizing inductor currents are substantially equal, and the resonant capacitor voltages are also substantially equal. The controller for a resonant converter according to claim 36, wherein when the resonant converter is operated in the normal state of the normal mode, the magnetizing inductor current has a positive peak and a negative peak. The resonant capacitor voltage has a first voltage value corresponding to the positive peak, a second voltage value corresponding to the negative peak, and an intermediate value. As described in claim 37, for a resonant converter The controller, wherein the first adjustment pulse is used to adjust the magnetizing inductor current and the resonant capacitor voltage to the positive peak value and the first voltage value, respectively. The controller for a resonant converter according to claim 37, wherein the first pulse group further includes at least one second adjustment pulse, which is connected to the second pulse group, and is used to The above resonance capacitor voltage is adjusted to the above intermediate value. The controller for a resonant converter according to claim 37, wherein the first pulse group further includes at least one second adjustment pulse, the first adjustment pulse being connected after the second adjustment pulse, The resonant capacitor voltage of the above resonant circuit is adjusted to the above intermediate value. The controller for a resonant converter according to claim 37, wherein a pulse width of the first adjustment pulse is adjusted by the resonance capacitor voltage and the magnetization inductor current to a first voltage value and a positive peak value. Time is determined.