CN202652058U - Soft start circuit with soft loading function - Google Patents

Abstract

The utility model discloses a soft start circuit with a soft loading function. The soft start circuit comprises a frequency measurement circuit and a counter circuit connected with each other via a wire; a delay circuit is connected with a duty ratio detection circuit via a second wire; the duty ratio detection circuit is connected with the counter circuit via a third wire; the counter circuit is connected with a digital-analog conversion circuit via a fourth wire; and the digital-analog conversion circuit is connected with a comparator circuit via a fifth wire. The soft start circuit solves problems that in a conventional automobile electronic regulator soft start circuit, a soft start capacitor with larger size cannot be integrated on a chip, a circuit application area is enlarged and the cost is increased, and requirements on intelligent control and soft start time cannot be satisfied.

Description

A kind of soft starting circuit with soft value-added tax function

Technical field

The utility model belongs to the automotive control circuit technical field, relates in particular to OnePlant the soft starting circuit with soft value-added tax function.

Background technology

Soft starting circuit refers to be applied to various power management ICs and suppresses the chip enable stage owing to power switch pipe damages power switch pipe and other devices and mechanical torque etc. occurs with the larger surge current of 100% duty ratio conducting generation; The effect of car electronic adjuster soft start function is: when load changes, reduce the variation of engine speed, duty ratio increases gradually when soft start works, and the belt of generator is within reason to be tightened.If adjuster does not have soft start, when chip the startup stage or load when increasing, the excitation duty ratio increases immediately, exciting current is along with increase, magnetic torque increases so that the load of automobile engine increases, and belt is along with anxiety, and the rotating speed of engine is very responsive to the variation of load, mechanical torque can occur and cause engine misses in the unexpected increase of this duty ratio, and soft start function will be avoided the generation of this adverse effect; At present, known soft starting circuit is the soft start voltage that obtains rising on the slope to capacitor charging by a current source, with soft start voltage and sawtooth voltage relatively, obtain the control signal that a duty ratio increases gradually and come the conducting of control switch pipe, thereby reach the purpose of soft start.The advantage of this method is to be simple and easy to usefulness, and shortcoming is to need a soft start capacitor to control soft-start time, and this electric capacity is often larger, and is difficult to flexible control, can't be integrated on the chip, and this will increase uses area and application cost.Especially this circuit of under low frequency, working of car electronic adjuster, should the startup stage realize that soft start realizes soft loading in normal work stage again, intelligent control is had relatively high expectations, soft-start time needs 3-5S, capacitive way can't be competent at.

Summary of the invention

The technical problems to be solved in the utility model: provide OnePlant the soft starting circuit with soft value-added tax function, to solve in the present car electronic adjuster soft starting circuit because employing soft start capacitor and electric capacity volume are larger, what cause can't be integrated on the chip, circuit application area change and cost increase, and can not satisfy the problems such as intelligent demand for control and soft-start time demand.

Technical solutions of the utility model:

OnePlant the soft starting circuit with soft value-added tax function, it comprises:

Frequency measurement circuit, the square wave incoming frequency that converts according to the generator phase voltage is determined the operating state of circuit, frequency measurement circuit is connected by wire with counter circuit;

Delay circuit, for duty detection circuit provides reset signal, delay circuit is connected by wire with duty detection circuit;

Duty detection circuit, for detection of the duty ratio in each excitation cycle, duty detection circuit is connected by wire with counter circuit;

Counter circuit provides digital input signals to D/A converting circuit, is connected by wire with D/A converting circuit;

D/A converting circuit changes the counter circuit digital input signals into analog signals, and to produce soft start voltage, D/A converting circuit is connected by wire with comparator circuit;

Comparator circuit compares according to the output signal of D/A converting circuit and the sawtooth signal of system's generation, exports a conducting that duty ratio pre-excitation signal removes the control switch pipe.

Frequency measurement circuit comprises that two bands reset, keep d type flip flop and latch of function, and two d type flip flops consist of one two counter, the exit of the termination latch that resets of two digit counters.

Duty detection circuit comprises that five digit counters and five latchs that five d type flip flops consist of form, and five d type flip flops form five digit counters.

Counter circuit comprises five five digit counters with the d type flip flop formation that can put number, reset and keep function.

The utility model beneficial effect:

The utility model circuit adopts the analog conversion circuit control of counting the number of words, frequency measurement circuit and duty detection circuit, not only realized the function of upper soft starting, and when when circuit works, causing voltage to descend on a large scale owing to the application of heavy load, this circuit can start soft value-added tax function, avoided heavy load to use heavy current impact and the mechanical torque phenomenon that causes, soft-start time is easy to control, can be integrated in the low frequency system, be easy to realize pre-excitation, can either the startup stage realize soft start function, again can be because the application of heavy load realizes soft value-added tax function when normal operation, solved in the present car electronic adjuster soft starting circuit and can't be integrated on the chip owing to what adopt that soft start capacitor and capacity ratio cause greatly, circuit application area change and cost increase, and can not satisfy the problems such as intelligent demand for control and soft-start time demand.

Description of drawings:

Fig. 1 is the utility model elementary diagram.

Embodiment:

OnePlant the soft starting circuit with soft value-added tax function, it comprises (see figure 1):

Frequency measurement circuit, the square wave incoming frequency that converts according to the generator phase voltage is determined the operating state of circuit, frequency measurement circuit is connected by wire with counter circuit, frequency measurement circuit comprises that counter and a latch that two bit strips reset form, reference frequency pulse input end phase_test is the exit of latch and by receiving the reset terminal of two digit counters after the time-delay, reference frequency pulse input end phase_test connects the narrow pulse signal that frequency is 1/2 times of incision speed-frequency, phase place input phase connects pulse signal as count pulse, if can be 1/2 times of narrow pulse signal cycle inside counting of cutting speed-frequency more than or equal to 2, then the phase frequency reaches the incision rotating speed, latch and be output as low level, permission counter circuit counting, the beginning soft start operation, withdraw from pre-excitation, otherwise counter circuit is in reset mode, does not count, and soft starting circuit is in the pre-excitation state.The pre-excitation duty ratio can be by setting overlapping resistance string value and the sawtooth waveforms of the first reference voltage terminal VH compare to determine, the magnitude of voltage of D/A converting circuit output was not exactly the value of the first reference voltage terminal VH when counter circuit was not counted, and the value of the first constant reference voltage terminal VH and sawtooth waveforms relatively obtain the pre-excitation signal of a constant duty ratio.

Delay circuit, for duty detection circuit provides reset signal, delay circuit is connected by wire with duty detection circuit, and the input of delay circuit is connected with the latch signal end latch of duty detection circuit, and output is connected with the internal counter reset terminal of duty detection circuit.

Duty detection circuit, duty ratio for detection of each excitation cycle, duty detection circuit is connected by wire with counter circuit, duty detection circuit comprises that five digit counters and five latchs that five d type flip flops consist of form, five d type flip flops form five digit counters, five outputs of duty detection circuit are connected with the several inputs of putting of counter circuit respectively, the output level of the latch signal end latch of duty detection circuit and the pwm control circuit of system disconnected, latch signal is provided and provides reset signal by delay circuit, the count pulse input cp1 of duty detection circuit is connected with system clock.

Counter circuit provides digital input signals to D/A converting circuit, is connected by wire with D/A converting circuit; Counter circuit has by five can put number, reset, five digit counters that keep the d type flip flop formation of function, rolling counters forward can maintain the original state when full and no longer count, finish soft start this moment, overflow end C end output high level, the gating AND circuit, as soft loading waiting signal, five outputs of counter circuit, five inputs corresponding with D/A converting circuit connect, count pulse input CP end is connected with the count pulse of control soft-start time, counter circuit overflow end C and being connected with an input of door, the soft loading end of another input termination with door, be connected with the number end PE that presets of counter with the output of door, put the number end and be connected with the corresponding output of duty detection circuit respectively for five of counter circuit.

D/A converting circuit changes the counter circuit digital input signals into analog signals, and to produce soft start voltage, D/A converting circuit is connected by wire with comparator circuit; D/A converting circuit is five digital to analog converter, D/A converting circuit adopts overlapping resistor string converter structure, the first reference voltage terminal VH and the second reference voltage terminal VL are the two ends of overlapping resistor string, connect upper voltage limit and the lower voltage limit of reference voltage in order to determine soft start voltage; The upper voltage limit of sawtooth waveforms of the present utility model is 3.5V, lower voltage limit is 2.5V, when D/A converting circuit is output as 3.2V and the comparator circuit comparison can obtain the pre-excitation duty ratio of 29% duty ratio, therefore the first reference voltage terminal VH is connected with the 3.2V reference voltage source, the second reference voltage terminal VL end is connected with the 2.5V reference voltage source, the input of the decoder circuit in the D/A converting circuit is connected with the output to low level of the high position of counter circuit respectively from a high position to the low level, and the output of D/A converting circuit is connected with the first input end of comparator circuit.

Comparator circuit, compare according to the output signal of D/A converting circuit and the sawtooth signal of system's generation, the conducting that output out output duty cycle pre-excitation signal removes the control switch pipe, the sawtooth signal that system produces is received the second input Vramp of comparator circuit.

The utility model operation principle: when circuit powers on, automobile just starts, the phase voltage frequency of automobile current generator is lower, and the termination that resets of two digit counters in the frequency measurement circuit is that frequency is the burst pulse of 1/2 times of incision speed-frequency, the phase frequency pulse is counted in the cycle in each burst pulse, if rolling counters forward to 2 item is overflowed, no longer count, keep original state, the latches overflow status then resetted to two digit counters when the burst pulse one-period finished, when overflowing, latch is output as low level, otherwise is high level, and the output of latch is the output of frequency measurement circuit.Therefore when latch is output as low level, phase frequency umber of pulse at 1/2 times of time counting of cutting frequency is described more than or equal to 2, namely the phase frequency is more than or equal to one times incision frequency.

In order to allow automobile easily start, when phase voltage is lower than one times of incision rotating speed, make adjuster be in a less fixed duty cycle conducting state, it is the pre-excitation state, therefore this soft starting circuit has designed the pre-excitation function, because the output of frequency measurement circuit is connected with the reset terminal R of counter circuit, when frequency measurement circuit is output as high level, its two digit counter is in reset mode, does not count.By obtaining the voltage that amplitude is identical with reference voltage after the D/A converting circuit conversion, this voltage compares by comparator circuit and sawtooth voltage, the output of comparator circuit just can obtain the conducting that the definite pre-excitation signal of a duty ratio removes the control switch pipe, just can easily control the duty ratio of pre-excitation state by the value of setting reference voltage.Namely determine the size of pre-excitation duty ratio by the value of setting reference voltage according to system's needs.

After the phase frequency reaches one times incision rotating speed, the frequency measurement circuit output low level, allow its two digit counter to begin counting, change by D/A converting circuit, thereby obtain a ramp voltage, this voltage and comparator circuit compare and just can obtain a duty ratio and increased gradually the soft start square-wave signal that reaches 100% duty ratio by pre-excitation state duty ratio.When its two digit counter count down to when overflowing, spill over is controlled two digit counters and is stopped counting, keeps overflow status, and soft start finishes, and soft start this moment is output as the waveform of duty ratio 100%.And because the output of soft starting circuit and the output of pwm controller are the relations of logical AND, this moment, the control of system was transferred the pwm controller to.

The latch signal end latch termination of duty detection circuit be the inversion signal of the pwm signal of pwm controller output, therefore when latch signal end latch end is low level, duty detection circuit allows the five digit counters counting of its inside, when latch signal end latch end is high level, the rising edge of latch signal end latch end gets off by the state latch of latch handle five digit counters this moment of inside, through after the delay circuit time-delay five digit counters being carried out zero clearing, guarantee to latch afterwards first to reset, duty detection circuit is just recorded the duty ratio of current pwm signal like this.Because also being D/A converting circuit, realizes by the sawtooth-wave circuit of this system, soft start is also used D/A converting circuit, as long as the clock of D/A converting circuit is identical, waits for putting when soft load signal arrives and count to the counter circuit the inside by reducible its duty ratio of soft starting circuit.Duty detection circuit is recording the duty ratio of upper excitation period p wm controller output.

The counter circuit spill over connects and door, this moment, soft load enable end LRC was ready, when heavy load is used, only meet soft loading environment, providing high level holds to LRC, at this moment the state that just allows duty detection circuit to record is put and is counted in the counter circuit, counter circuit begins counting, the excitation duty ratio of the pwm controller output of this moment increased gradually from the duty ratio in a upper excitation cycle, avoided the application of heavy load so that voltage drop, the excitation duty ratio increases suddenly, realizes soft value-added tax function.

Claims (4)

1. OnePlant the soft starting circuit with soft value-added tax function, it is characterized in that: it comprises that frequency measurement circuit is connected by wire with counter circuit, delay circuit is connected by wire with duty detection circuit, duty detection circuit is connected by wire with counter circuit, counter circuit is connected by wire with D/A converting circuit, and D/A converting circuit is connected by wire with comparator circuit.

2. a kind of soft starting circuit with soft value-added tax function according to claim 1, it is characterized in that: frequency measurement circuit comprises that two bands reset, keep d type flip flop and latch of function, two d type flip flops consist of one two counter, the exit of the termination latch that resets of two digit counters.

3. a kind of soft starting circuit with soft value-added tax function according to claim 1 is characterized in that: duty detection circuit comprises that five digit counters and five latchs that five d type flip flops consist of form, and five d type flip flops form five digit counters.

4. a kind of soft starting circuit with soft value-added tax function according to claim 1 is characterized in that: counter circuit comprises five five digit counters with the d type flip flop formation that can put number, reset and keep function.