TWI716305B - Pulse generator - Google Patents

Abstract

A pulse generator is provided. The pulse generator includes a trigger circuit, a processing circuit and a pulse generating circuit. The trigger circuit detects a zero-crossing point of an AC power source. The AC power source supplies electronic devices to operate at an operating power. The trigger circuit generates a trigger signal when a zero-crossing point is detected. After the trigger circuit generates the trigger signal, the processing circuit outputs a width initial value corresponding to the operating power, and outputs a width intermediate value between the width initial value and the width target value, and outputs the width target value when the width intermediate value reaches the width target value after the width intermediate value changing a change amount. The pulse generating circuit generates pulse signals with different pulse widths at different time points according to the initial width value, the intermediate width value, and the width target value output by the processing circuit.

Description

Pulse signal generator

This case is about a pulse signal generator, and especially a pulse signal generator that generates variable pulse width.

The conventional electromagnetic heating device includes a pulse generator. The pulse generator is used to drive the resonant circuit on the coil in the electromagnetic heating device. Under the same operating power, the pulse generator can generate a pulse signal with a fixed width. When operating at the maximum power (for example, 2100W), it will cause severe electromagnetic interference (EMI). In recent years, the concept of health and environmental protection has risen. Countries around the world have successively required all kinds of electronic products to limit EMI emission and consider the problems of electromagnetic immunity (EMC) and electromagnetic compatibility (EMS). In response to the needs of various countries, the country has formulated various electromagnetic interference EMI /EMC/EMS and other standard specifications and implementation schedules have become more and more stringent in terms of requirements. All electronic products must pass the country's specific authorized units or institutions, and test and pass in accordance with the standard specifications before the products can be sold.

Therefore, if the EMI problem is not paid attention to in the product development stage, at the later stage of the product development, if only adding anti-EMI components through the external printed circuit board, the EMI can only be reduced to a limited extent, but the serious EMI problem cannot be solved. At this time, it may need to redesign Products, delay time to market. Therefore, from the perspective of the main sources of EMI, the EMI problem occurs when the electromagnetic heating device is operating at low power. The insulated gate bipolar transistor (IGBT) has the problem of hard conduction, and when the electromagnetic heating device is operating at high power, the IGBT The operating voltage is too high. In order to effectively reduce the hard turn-on problem of the IGBT, the distance between the coil plate and the furnace surface has been increased in the conventional electromagnetic heating device, but the IGBT generates an excessively high back pressure, which makes the electromagnetic heating device unable to operate at the maximum power. Cause more serious EMI problems.

In one embodiment, a pulse signal generator includes a trigger circuit, a processing circuit, and a pulse generating circuit. The trigger circuit detects a zero-crossing point of an AC power source. The AC power supply supplies the electronic device to operate at an operating power. The trigger circuit generates a trigger signal when the zero-crossing point is detected. After the trigger circuit generates the trigger signal, the processing circuit outputs a first width initial value corresponding to the operating power, and outputs a first width intermediate value when a first preset time has elapsed, and the first width intermediate value is the first width initial value Change a first change amount to approach the first width target value, and determine whether the first width intermediate value changes toward the first width target value by a second change amount to reach the first width target value, when the judgment is no, the processing circuit When a second preset time has elapsed after the first intermediate value of the width is output, a second intermediate width value is output. The second intermediate value of the width If yes, the processing circuit outputs the first width target value when the second preset time elapses after outputting the first width intermediate value. The pulse generating circuit generates a first pulse signal whose pulse width is one of the first width initial values when the processing circuit outputs the first width initial value, and when the processing circuit outputs the first width intermediate value, generates a pulse width that is within the first width intermediate value A second pulse signal, and when the processing circuit outputs a second width intermediate value, a third pulse signal with a pulse width of one of the second width intermediate values is generated, and when the processing circuit outputs a first width target value, a pulse width of the first The fourth pulse signal of the width target value.

FIG. 1 is a block diagram of an embodiment of a pulse signal generator 1 suitable for electronic devices according to the present application. Please refer to Figure 1. The pulse signal generator 1 can generate the pulse signal S4 required by the electronic device to operate at the operating power set by the user. The electronic device can be an induction cooker, a microwave oven or an induction heating (IH) electric cooker. The power can be 1600 watts, 1800 watts or 2000 watts. If the electronic device is operated at 2000 watts, the pulse signal generator 1 can generate pulse signals S4 with different pulse widths corresponding to the operating power of 2000 watts, so that the pulse signals S4 with different pulse widths can generate an average power of 2000 watts of operating power; if the electronic device operates at 1600 watts, the pulse signal generator 1 can generate pulse signals S4 with different pulse widths corresponding to 1600 watts of operating power, so that the pulse signals S4 with different pulse widths have a preset time The average power generated within the length is 1600 watts of operating power, and so on, so I won’t repeat it here.

As shown in FIG. 1, the pulse signal generator 1 includes a trigger circuit 11, a processing circuit 12 and a pulse generating circuit 13. The processing circuit 12 is coupled between the trigger circuit 11 and the pulse generating circuit 13. When the electronic device receives AC power and operates at the operating power set by the user, the trigger circuit 11 detects the zero-crossing point of the AC power, and the trigger circuit 11 generates the trigger signal S1 when the zero-crossing point is detected. After the trigger circuit 11 generates the trigger signal S1, according to the operating power of the electronic device, the processing circuit 12 outputs a corresponding initial width value (for convenience of description, hereinafter referred to as the first width initial value) as a pulse width signal at the first time point S3, and output a width intermediate value (hereinafter referred to as the first width intermediate value) at the second time point when a preset time (hereinafter referred to as the first preset time) has elapsed as a pulse width signal S3, the first width is intermediate The value is located between the first width initial value and the first width target value, and the first width intermediate value is changed from the first width initial value by a first change amount to approach a width target value (hereinafter referred to as the first width target value) And, the processing circuit 12 determines whether the first width intermediate value reaches the first width target value after changing a second change amount toward the first width target value.

When the judgment is "No", it means that the first width intermediate value after the change has not reached the first width target value, so after a preset time (hereinafter referred to as the second preset time) has passed since the second time point, The processing circuit 12 outputs another intermediate width value (hereinafter referred to as the second intermediate width value) at the third time point as the pulse width signal S3, the second intermediate width value is located between the first intermediate width value and the first width target value, The second width intermediate value changes the first width intermediate value by the aforementioned second change amount to approach the first width target value. Based on this, the processing circuit 12 can continuously output the pulse width signal S3 that does not reach the first width target value, the intermediate value of the width, until the processing circuit 12 determines (that is, judges "yes") a change in the intermediate width value and a change amount After reaching the first width target value, the processing circuit 12 outputs the first width target value as the pulse width signal S3 at a time point after a predetermined time point has passed after the previous output width intermediate value. Point in time Pulse Width Remarks The first time 25 μs Initial value of first width Second time point 24.5 μs First width median Third time point 24 μs Middle value of second width Fourth time point 23.5 μs Other median width Nth time point 20.5 μs Other median width N+1 time point 20 μs First width target value N+2 time point 20 μs First width target value Table I)

For example, as shown in Table (1), the initial value of the first width is 25 μs, the target value of the first width is 20 μs, the first change is 0.5 μs, and the second change is 0.5 μs. The circuit 12 outputs the first width initial value of 25 μs at the first time point, and outputs the first width intermediate value of 24.5 μs at the second time point. The processing circuit 12 determines that the first width intermediate value does not reach the first width Therefore, the processing circuit 12 outputs the second width intermediate value of 24 μs at the third time point. When the processing circuit 12 determines that the intermediate value of each width does not reach the first width target value of 20 μs, the processing circuit 12 At different time points, the first intermediate value of the output at the previous time point is changed by 0.5 μs and output, so that the intermediate value of each width gradually decreases and approaches 20 μs, until the processing circuit 12 determines that the output at the nth time point is The first width target value is reached after the intermediate value of the width of 20.5 μs changes by 0.5 μs, the processing circuit 12 outputs the first width target value of 20 μs at the n+1th time point, and can output at the n+2th time point It is the first width target value of 20 μs.

Among them, it is worth noting that in the foregoing embodiment, the first width target value is less than the first width initial value. Therefore, the intermediate value of each width is in a decreasing relationship. However, this case is not limited to this. For different operating powers of the electronic device or the electronic device, the first width target value can also be greater than the first width initial value, so that the intermediate values of the widths have an increasing relationship.

According to each pulse width signal S3 output by the processing circuit 12, the pulse generating circuit 13 can generate a pulse signal S4 with a corresponding pulse width according to the output of the processing circuit 12 to generate a pulse signal S4 with different pulse widths. For example, the processing circuit 12 outputs the aforementioned first width initial value as a pulse width signal S3, the pulse generating circuit 13 generates a first pulse signal with a pulse width of 25 μs, and the processing circuit 12 outputs the aforementioned first width intermediate value as a pulse width signal S3, the pulse generating circuit 13 generates a second pulse signal with a pulse width of 24.5 μs, the processing circuit 12 outputs the aforementioned second width intermediate value pulse width signal S3, and the pulse generating circuit 13 generates a third pulse signal with a pulse width of 24 μs , And so on, until the processing circuit 12 outputs the aforementioned first width target value of the pulse width signal S3, and the pulse generating circuit 13 generates the fourth pulse signal with a pulse width of 20 μs.

Based on this, as shown in FIG. 2, the pulse generating circuit 13 can generate a pulse signal S4 with a decreasing or increasing pulse width, so that the electronic device can provide the operating power set by the user, and at the same time can reduce the electronic device's emission at a single frequency. Strength to reduce EMI influence and meet EMI standards. In addition, the pulse generating circuit 13 sends a pulse signal S4 with a variable width to the switching circuit implemented by the insulated gate bipolar transistor in the electronic device, so that the back pressure generated by the insulated gate bipolar transistor can be reduced and the electronic device can be operated At maximum power.

In one embodiment, the pulse signal generator 1 further includes a timing circuit 14, and the timing circuit 14 is coupled between the trigger circuit 11 and the processing circuit 12. The timing circuit 14 receives the trigger signal S1 generated by the trigger circuit 11 to know that the AC power has passed the zero-crossing point, and the timing circuit 14 starts timing when the trigger signal S1 is received. 3, the timing circuit 14 time two time intervals T1 and T2 (hereinafter referred to as the first time interval T1 and the second time interval T2 respectively) according to a preset design. In the first time interval T1, the processing circuit 12 is The fixed pulse width value is output as the pulse width signal S3. For example, the processing circuit 12 continuously outputs the aforementioned initial value of the first width, so that the pulse generating circuit 13 generates a pulse signal with a fixed pulse width of 25 μs in the first time interval T1 S4; In the second time interval T2, the processing circuit 12 begins to output a pulse width signal S3 that gradually changes from the initial value of the first width to the first width target value, so that the pulse generating circuit 13 is in the second time interval In T2, a pulse signal S4 with a variable width (ie, the aforementioned first pulse signal, second pulse signal, third pulse signal, and fourth pulse signal) is generated.

Accordingly, the timing circuit 14 sends a timing signal S2 to the processing circuit 12, so that the processing circuit 12 knows whether the AC power has entered the second time interval T2 after the zero-crossing point, and the processing circuit 12 can learn from the previous time according to the timing signal S2 Whether the point has passed the first preset time and the second preset time, the processing circuit 12 can output the width at the corresponding time point in the second time interval T2 (for example, the aforementioned first time point to the n+2th time point) The initial value, the intermediate value of each width and the target value of the width are as shown in Table (1). It is worth noting that, according to the time length of the second time interval T2, the processing circuit 12 may output the first width target value at the last time point in the second time interval T2, or output the first width initial value and the first width A width target value has not changed to any width intermediate value of the first width target value. Hereinafter, the pulse width output by the processing circuit 12 at the last time point in the second time interval T2 is called the first width end value .

Furthermore, as shown in FIG. 3, the timing circuit 14 further counts a third time interval T3. In the third time interval T3, the processing circuit 12 outputs a pulse width value according to the first width end value and a second width target value The pulse width signal S3, that is, the processing circuit 12 can output each width intermediate value gradually changing from the first width end value to the second width target value, and the second width target value is different from the first width target value. In detail, the processing circuit 12 outputs the first width end value to change to the second width target value by a third amount of change at one of the time points (hereinafter referred to as the first time point) in the third time interval T3 according to the timing signal S2 The latter intermediate value of the width (hereinafter referred to as the third intermediate value of the width) is the pulse width signal S3, and the processing circuit 12 determines whether the third intermediate value of the width reaches the second width after a fourth variation toward the second width target value. Target value. When the judgment is "No", it means that the changed third width intermediate value has not reached the second width target value. Therefore, according to the timing signal S2, a preset time has elapsed since the first time point in the third time interval T3 (Hereinafter referred to as the third preset time), the processing circuit 12 outputs another intermediate width value (hereinafter referred to as the fourth intermediate width value) at the second time point as the pulse width signal S3, and the fourth intermediate width value is located in the third The width intermediate value is between the second width target value, and the fourth width intermediate value changes the third width intermediate value by the aforementioned fourth change amount to approach the second width target value.

Based on this, the processing circuit 12 can continuously output the pulse width signal S3 that does not reach the second width target value, the intermediate value of the width, until the processing circuit 12 determines (ie, judges "Yes") a change in the intermediate width value and a change amount After reaching the second width target value, the processing circuit 12 outputs the second width target value as the pulse width signal S3 at a time point after a preset time has passed after the previous output width intermediate value. The third time interval T3 Point in time Pulse Width Remarks The first time 20.5 μs Middle value of third width Second time point 21 μs Middle value of fourth width Nth time point 22 μs Other median width N+1 time point 22.5 μs Second width target value N+2 time point 22.5 μs Second width target value Table II)

For example, as shown in Table (2), taking the third variation and the fourth variation of 0.5 μs and the second width target value of 22.5 μs as an example, the third width output by the processing circuit 12 at the first time point The intermediate value of the first width target value (ie, 20 μs) changes 0.5 μs to 22.5 μs, so that the third width intermediate value is 20.5 μs, and the processing circuit 12 determines that the third width intermediate value changes to 22.5 μs after 0.5 μs. The second width target value is reached, so the processing circuit 12 outputs the fourth width intermediate value of 21 μs at the second time point. When the processing circuit 12 determines that the width intermediate values have not reached the second width target value of 22.5 μs, The processing circuit 12 changes the intermediate value of the output at the previous time point by 0.5 μs at different time points and outputs it, so that the intermediate value of each width gradually increases and approaches 22.5 μs, until the processing circuit 12 determines the nth time point The output is the second width target value of 22 μs after the intermediate value of the width changes by 0.5 μs, the processing circuit 12 outputs the second width target value of 22.5 μs at the n+1th time point, and can be at the n+2th time point The output is the second width target value of 22.5 μs.

It is worth noting that, according to the time length of the third time interval T3, the processing circuit 12 may output the second width target value at the last time point in the third time interval T3, or output the first width end value and the first width end value. Any width intermediate value that has not changed between the two width target values to the second width target value, the pulse width output by the processing circuit 12 at the last time point in the third time interval T3 is referred to as the second width end value below .

Therefore, the pulse generating circuit 13 can generate a pulse signal S4 corresponding to the pulse width signal S3 according to the pulse width signal S3 output by the processing circuit 12 in the third time interval T3. For example, the processing circuit 12 outputs the aforementioned third width intermediate value as a pulse width signal S3, the pulse generating circuit 13 generates a fifth pulse signal with a pulse width of 20.5 μs, and the processing circuit 12 outputs the aforementioned fourth width intermediate value as a pulse width signal S3: The pulse generating circuit 13 generates a sixth pulse signal with a pulse width of 21 μs, and so on, until the processing circuit 12 outputs the aforementioned second target value of the pulse width signal S3, and the pulse generating circuit 13 generates a pulse width of 22.5 μs The seventh pulse signal. Among them, it is worth noting that the foregoing embodiment is based on the example that the second width target value is greater than the first width target value. Therefore, the intermediate width values are in an increasing relationship. However, this case is not limited to this. For different operating powers of the electronic device or the electronic device, the second width target value can also be smaller than the first width target value, so that the intermediate values of the widths show a decreasing relationship. As shown in FIG. 4, the pulse generating circuit 13 can output a pulse signal S4 whose pulse width changes from decreasing to increasing, or output a pulse signal S4 whose pulse width changes from increasing to decreasing.

In one embodiment, the timing circuit 14 may use three registers to perform timing procedures for the three time intervals T1, T2, and T3.

In an embodiment, the aforementioned first preset time, second preset time, and third preset time may be the same or different, and the processing circuit 12 may determine each preset time according to the operating power of the electronic device. For example, the first preset time, the second preset time, and the third preset time may all be three clock cycle times, or the first preset time and the first preset time may be three clock cycle times respectively And five clock cycle times, the third preset time is two clock cycle times. Furthermore, the aforementioned first variation, second variation, third variation, and fourth variation may be the same or different, and the processing circuit 12 can determine each variation according to the operating power of the electronic device. For example, the aforementioned first change, second change, third change, and fourth change are all 0.5 μs, or the first change and second change are 0.5 μs and 1.5 μs, respectively, and the third change And the fourth change are 1.5 μs and 1 μs respectively.

In an embodiment, when the amount of change between the pulse width signals S3 output by the processing circuit 12 at different time points is different, the processing circuit 12 is between the pulse width signals S3 output by the processing circuit 12 during the second time interval T2. The difference between the variation of the pulse width signal S3 output by the processing circuit 12 in the third time interval T3 is that one is greater than zero and the other is less than zero. . Take the aforementioned first change, second change, third change, and fourth change as an example, when the aforementioned first change, second change, third change, and fourth change are different When the same, the difference between the first variation and the second variation (hereinafter referred to as the first difference) and the difference between the third variation and the fourth variation (hereinafter referred to as the second difference) One is greater than zero and the other is less than zero. For example, the first change is greater than zero and the second change is less than zero, or the first change is less than zero and the second change is greater than zero, And the absolute value of the first difference is equal to the absolute value of the second difference. Time interval Point in time Pulse Width Variation Difference The second time interval T2 The first time 80 μs 4 μs +1 μs Second time point 84 μs 5 μs +1 μs Third time point 89 μs 6 μs +1 μs Fourth time point 95 μs 7 μs +1 μs Fifth time point 102 μs 8 μs +1 μs The third time interval T3 Sixth time 110 μs 7 μs -1 μs Seventh time point 117 μs 6 μs -1 μs Eighth time point 123 μs 5 μs -1 μs Ninth time point 128 μs 4 μs -1 μs Table (three)

For example, as shown in Table (3), taking the first width target value and the second width target value of 102 μs and 128 μs respectively as an example, in the second time interval T2, the processing circuit 12 can be set to The variation of μs, 5 μs, 6 μs, 7 μs, and 8 μs output the increasing pulse width signal S3 to the pulse generating circuit 13, that is, the difference between the variation in the second time interval T2 is +1 μs; In the third time interval T3, the processing circuit 12 can output the increasing pulse width signals S3 to the pulse generating circuit 13 according to the variation of 7 μs, 6 μs, 5 μs and 4 μs respectively, which is the third time The difference between the changes in the interval T3 is -1 μs and the absolute values of the differences are equal. Therefore, as shown in FIG. 5, the change trend of each change in the second time interval T2 (hereinafter referred to as the first change trend) and the change trend of each change in the third time interval T3 (hereinafter referred to as the second The changing trend) can present various curves, such as a parabola, and one of the first changing trend and the second changing trend is increasing and the other is decreasing.

In one embodiment, as shown in FIG. 3, the timing circuit 14 further counts a fourth time interval T4 before the AC power source passes the zero-crossing point next time to generate the timing signal S2 to the processing circuit 12. The processing circuit 12 outputs a fixed pulse width value as the pulse width signal S3 in the fourth time interval T4. For example, the processing circuit 12 continuously outputs the second width target value of 22.5 μs in the fourth time interval T4, or continuously Ground outputs the second end value of the width, for example, 21.5 μs, so that the pulse generating circuit 13 generates a pulse signal S4 with a fixed pulse width of 22.5 μs or 21.5 μs in the fourth time interval T4.

In one embodiment, the pulse signal generator 1 can be implemented by a microcontroller (MCU), or the pulse signal generator 1 can be a special application integrated circuit (ASIC), that is, the pulse signal generator 1 is implemented in a hardware description language For example, the verilog language is designed and implemented as an integrated circuit chip, so that it can avoid the problem of dynamically adjusting the pulse width by software calculations that is limited by the software processing scheduling priority, and avoiding dynamic adjustment under the limited resources of the microcontroller The pulse width occupies most of the processing resources of the microcontroller, so that it cannot handle other needs in time. Furthermore, the aforementioned changes, the initial values of the widths, and the target values of the widths can be stored in a storage circuit coupled to the processing circuit 12, and the processing circuit 12 can instantly read from the storage circuit according to the operating power of the electronic device The corresponding amount of change, the initial value of the width, and the target value of the width are sent to the pulse generating circuit 13 to generate a corresponding pulse signal S4, so that the electronic device can provide the operating power set by the user.

In summary, according to an embodiment of the pulse signal generator of the present application, the pulse generating circuit can generate pulse signals with decreasing or increasing pulse width to reduce the intensity of the electronic device emitted at a single frequency, so that the influence of EMI can be reduced. It complies with EMI standards, and at the same time enables the electronic device to provide the operating power set by the user to heat the object. In addition, the pulse generating circuit sends a pulse signal with a variable width to the switching circuit implemented by the insulated gate bipolar transistor in the electronic device, so that the back pressure generated by the insulated gate bipolar transistor can be reduced, so that the electronic device can operate at maximum power. Moreover, the implementation of hardware circuits can avoid the problem of being limited to the priority of software processing and avoid occupying most of the processing resources of the microcontroller.

Although this case has been disclosed by the examples above, it is not intended to limit the case. Anyone with ordinary knowledge in the technical field can make some changes and modifications without departing from the spirit and scope of the case. Therefore, the scope of protection of this case The scope of the patent application attached hereafter shall prevail.

1: Pulse signal generator 11: Trigger circuit 12: Processing circuit 13: Pulse generating circuit 14: Timing circuit S1: Trigger signal S2: timing signal S3: Pulse width signal S4: Pulse signal T1: the first time interval T2: second time interval T3: The third time interval T4: The fourth time interval

[Figure 1] is a block diagram of an embodiment of a pulse signal generator suitable for electronic devices according to the present application. [Fig. 2] is a waveform diagram of an embodiment of the pulse generating circuit in Fig. 1 generating different pulse signals with different pulse widths. [FIG. 3] A schematic diagram of an embodiment of a time interval timed by the timing circuit of FIG. 1. [FIG. 4] It is a waveform diagram of another embodiment in which the pulse generating circuit of FIG. 1 generates different pulse signals with different pulse widths. [FIG. 5] A schematic diagram of an embodiment of the variation trend of different pulse widths output by the processing circuit of FIG. 1 at different time points.

1: Pulse signal generator

11: Trigger circuit

12: Processing circuit

13: Pulse generating circuit

14: Timing circuit

S1: Trigger signal

S2: timing signal

S3: Pulse width signal

S4: Pulse signal

Claims (9)

A pulse signal generator for providing a pulse signal required when an electronic device is operated at an operating power, comprising: a trigger circuit for detecting a zero-crossing point of an AC power source that supplies the electronic device Operating at the operating power, the trigger circuit generates a trigger signal when the zero-crossing point is detected; a processing circuit coupled to the trigger circuit for outputting one of the corresponding operating powers after the trigger circuit generates the trigger signal A first width initial value, and a first width intermediate value is output when a first preset time has elapsed. The first width intermediate value is changed by a first variation from the first width initial value to approach a first width target Value, and determine whether the first width intermediate value reaches the first width target value after a second change amount toward the first width target value. When the judgment is no, the processing circuit is outputting the first width intermediate value After a second preset time has elapsed, a second width intermediate value is output, the second width intermediate value is changed by the first width intermediate value by the second change amount to approach the first width target value, when the judgment is yes , The processing circuit outputs the first width target value when the second preset time passes after outputting the first width intermediate value; a pulse generating circuit is coupled to the processing circuit for outputting the first width in the processing circuit When the width is an initial value, a first pulse signal with a pulse width of the first width initial value is generated, and when the processing circuit outputs the first width intermediate value, a second pulse signal with a pulse width equal to the first width intermediate value is generated , And when the processing circuit outputs the second width intermediate value, a third pulse signal with a pulse width of one of the second width intermediate values is generated, and when the processing circuit outputs the first width target value, a pulse width is generated as the first A fourth pulse signal with a target width; and A timing circuit is coupled to the trigger circuit, the timing circuit is triggered by the trigger signal to time a first time interval and a second time interval, and the pulse generating circuit generates a plurality of pulses with a fixed width in the first time interval Pulse signal, the pulse generating circuit starts to generate the first width initial value, the first width intermediate value, the second width intermediate value, and the first width target value output by the processing circuit during the second time interval The first pulse signal, the second pulse signal, the third pulse signal, and the fourth pulse signal. The pulse signal generator according to claim 1, wherein when the first width target value is greater than the first width initial value, the first width intermediate value is greater than the first width initial value and the second width intermediate value is greater than Or equal to the first width intermediate value, when the first width target value is less than the first width initial value, the first width intermediate value is less than the first width initial value and the second width intermediate value is less than or equal to the first width The median value of a width. The pulse signal generator according to claim 1, wherein the timing circuit further counts a third time interval, and the processing circuit outputs the first width target value or lies between the first width initial value and the A third width intermediate value between the first width target values changes toward a second width target value after a third change amount, and it is determined that the third width intermediate value changes toward the second width target value Whether the second width target value is reached after a fourth change amount, when the judgment is no, the processing circuit outputs a fourth width middle value when a third preset time passes after outputting the third width middle value, the The fourth width intermediate value changes the third width intermediate value by the fourth change amount to approach the second width target value. When the judgment is yes, the processing circuit passes through the third preset after outputting the third width intermediate value. When setting the time, output the second width target value; Wherein, the pulse generating circuit further generates a fifth pulse signal whose pulse width is one of the third width intermediate values when the processing circuit outputs the third width intermediate value, and generates when the processing circuit outputs the fourth width intermediate value The pulse width is a sixth pulse signal of the intermediate value of the fourth width, and when the processing circuit outputs the second width target value, a seventh pulse signal having the pulse width of the second width target value is generated. The pulse signal generator according to claim 3, wherein the processing circuit determines whether the first preset time, the second preset time, and the third preset time are equal or not equal according to the operating power. The pulse signal generator according to claim 3, wherein the processing circuit determines according to the operating power that the first variation is equal to or not equal to the second variation, and the third variation is equal to or not equal to the fourth variation . The pulse signal generator according to claim 3, wherein when the difference between the first change and the second change is greater than zero, the difference between the third change and the fourth change The value is less than zero, and when the difference between the first variation and the second variation is less than zero, the difference between the third variation and the fourth variation is greater than zero. The pulse signal generator according to claim 6, wherein the absolute value of the difference between the first change and the second change is equal to the difference between the third change and the fourth change Absolute value. The pulse signal generator according to claim 3, wherein after the timing circuit counts the third time interval, the timing circuit counts a fourth time interval before the AC power source passes the next zero-crossing point, the pulse generating circuit A complex pulse signal with a fixed pulse width is generated in the fourth time interval. The pulse signal generator according to claim 1, wherein the electronic device includes a switching circuit, the switching circuit is implemented by an insulated gate bipolar transistor, and the pulse generating circuit is coupled to the switching circuit to output the first pulse signal , The second pulse signal, the third pulse signal and the fourth pulse signal to the switch circuit.

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