CN115514224A - Self-adaptive slope compensation method and circuit of multiphase control circuit - Google Patents
Self-adaptive slope compensation method and circuit of multiphase control circuit Download PDFInfo
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- H—ELECTRICITY
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- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M3/00—Conversion of dc power input into dc power output
- H02M3/02—Conversion of dc power input into dc power output without intermediate conversion into ac
- H02M3/04—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters
- H02M3/10—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
- H02M3/145—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
- H02M3/155—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only
- H02M3/156—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only with automatic control of output voltage or current, e.g. switching regulators
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Abstract
A method and a circuit for adaptive slope compensation of a multi-phase control circuit are characterized in that the method comprises the following steps: step 1, setting a slope compensation time limit of a slope compensation unit in the multi-phase control circuit based on a power supply voltage of the multi-phase control circuit, load limitation of an inductive current sampling signal, a conduction slope of an upper power tube and a conduction slope of the slope compensation unit; and 2, realizing feedback control on the multi-phase control circuit by adopting the slope compensation time limit and the pulse width modulation signal together. The circuit comprises a slope compensation delay unit, an AND gate, a NOT gate, a switch tube, a compensation capacitor, a bias current source, a voltage-controlled current source, a resistor and a superposition circuit, and is used for realizing the self-adaptive slope compensation method. The invention can prevent the control signal difference in the adjacent phases in the circuit from being overlarge by adjusting the highest compensation time of the slope compensation in each period, thereby ensuring the stability of the whole system.
Description
Technical Field
The present invention relates to the field of integrated circuits, and more particularly, to a method and a circuit for adaptive slope compensation of a multi-phase control circuit.
Background
The multiphase voltage converter is generally composed of a group of power level devices connected in parallel, each converter has independent inductance and power devices to realize independent voltage control, multiple paths of the converters are combined to be called multiphase, and through the mode of parallel connection of the multiphase, each phase is continuously switched at equal intervals and executes a corresponding voltage conversion function. Compared with the common single-phase voltage converter, the multi-phase voltage converter can reduce the output capacitance, improve the thermal performance and efficiency of the circuit under the condition of increasing the load current, improve the overshoot and the dive of the output in the transient process of the load, and has good output characteristics, thereby being widely applied. In addition, in the multi-phase voltage converter, in order to prevent the subharmonic oscillation problem, an independent slope compensation circuit may be provided for each phase.
However, for multi-phase voltage converters in which a slope compensation circuit is present, there are often problems as follows: the sum of the slope compensation and the slope provided by the upper power tube in the current phase is too high, and the power supply voltage is not enough to provide the high fast compensation, so that the transient response displayed by the circuit cannot meet the requirement of the design index. Meanwhile, the circuit of the next phase is also controlled by the pulse width modulation signal in the current phase, so that the output of the slope compensation signals in two adjacent phases is difficult to match, the actual switching time of the upper power tube and the lower power tube in the two adjacent phases is staggered, and the time of the difference of the switching periods exceeds a fixed period, so that the whole system loses stability.
In view of the above problems, the present invention provides an adaptive slope compensation method and circuit for a multi-phase control circuit.
Disclosure of Invention
In order to solve the defects in the prior art, the invention provides a self-adaptive slope compensation method and a self-adaptive slope compensation circuit of a multi-phase control circuit, which prevent overlarge control signal difference in adjacent phases in the circuit and ensure the stability of the whole system by adjusting the highest compensation time of slope compensation in each period.
The invention adopts the following technical scheme.
The invention relates to a first aspect of an adaptive slope compensation method of a multi-phase control circuit, which comprises the following steps: step 1, setting a slope compensation time limit of a slope compensation unit in the multi-phase control circuit based on the power supply voltage of the multi-phase control circuit, the load limit of an inductive current sampling signal, the conduction slope of an upper power tube and the conduction slope of the slope compensation unit; and 2, realizing feedback control on the multi-phase control circuit by adopting a slope compensation time limit and a pulse width modulation signal together.
Preferably, the first and second liquid crystal materials are,
wherein T is a slope compensation time limit,
k S1_i the conduction slope of the upper power tube in the ith phase is determined by the inductance L in the ith phase i Sampling resistor R i It is determined that,
k ramp_i for the conduction slope of the slope compensation unit in the ith phase, the current I of the current source is biased by the current in the ith phase bias Capacitance value C of the compensation capacitor i It is determined that,
V CS_load_max the maximum DC value of the inductor current sampling signal is determined by the maximum value of the currently applied load ILOAD,
V dd is the supply voltage of the multi-phase control circuit,
V dsat to maintain the saturated drain-source voltage of the charging current source in a saturated state.
Preferably, the slope compensation time limit is an integral multiple of the switching frequency of the upper and lower power tubes in the multi-phase control circuit.
The invention relates to a self-adaptive slope compensation circuit of a multiphase control circuit, which comprises a slope compensation delay unit, an AND gate, a NOT gate, a switch tube, a compensation capacitor, a bias current source, a voltage-controlled current source, a resistor and a superposition circuit; the first input end of the slope compensation delay unit is connected with the pulse width modulation signal of the ith phase in the multi-phase control circuit, the second input end of the slope compensation delay unit is connected with the clock signal, and the output end of the slope compensation delay unit is connected with the second input end of the AND gate; the first input end of the AND gate is connected with the pulse width modulation signal of the ith phase in the multiphase control circuit, and the input end of the output end of the NAND gate is connected; the input end of the NOT gate is connected with the grid electrode of the switch tube, the source drain electrode of the switch tube is connected in parallel with two ends of the compensation capacitor, one end of the compensation capacitor is connected with power voltage through a bias current source, and the other end of the compensation capacitor is grounded; the connection point of the bias current source and the compensation capacitor is connected to the positive phase input end of the voltage-controlled current source, the negative phase input end of the voltage-controlled current source is grounded, and the output end of the voltage-controlled current source is connected to the first input end of the superposition circuit after passing through the resistor; the second input end of the superposition circuit is connected to the inductive current peak value sampling signal VCS _ i of the ith phase, and the output end of the superposition circuit generates a feedback control signal of the ith phase.
Compared with the prior art, the self-adaptive slope compensation method and the self-adaptive slope compensation circuit of the multiphase control circuit have the advantages that the maximum compensation time of slope compensation in each period can be adjusted, the control signal difference in adjacent phases in the circuit is prevented from being overlarge, and therefore the stability of the whole system is ensured.
Drawings
FIG. 1 is a schematic circuit diagram of a multi-phase control circuit in the prior art;
FIG. 2 is a schematic diagram of a circuit structure of a slope compensation unit in a multi-phase control circuit in the prior art;
FIG. 3 is a timing diagram of the output of the compensation control signal provided by the slope compensation unit in the multi-phase control circuit according to the prior art;
FIG. 4 is a schematic diagram of an adaptive slope compensation circuit of a multi-phase control circuit according to the present invention;
FIG. 5 is a timing diagram of the output of the compensation control signal provided by the adaptive slope compensation circuit of the multi-phase control circuit according to the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention clearer, the technical solutions of the present invention will be described clearly and completely in the following with reference to the accompanying drawings in the embodiments of the present invention. The embodiments described in this application are only a part of the embodiments of the present invention, and not all embodiments. All other embodiments obtained by a person skilled in the art without any inventive step based on the spirit of the present invention are within the scope of the present invention.
Fig. 1 is a schematic circuit diagram of a multiphase control circuit in the prior art. As shown in fig. 1, the structure of a multiphase control circuit used in the prior art generally comprises a plurality of identical control phase branches. In each branch, VIN and VOUT respectively represent the input voltage and the output voltage of the circuit, and S1 and S2 respectively represent the upper power switch tube and the lower power switch tube of each phase; the signal EAO represents an error amplification signal between the feedback of the signal VOUT and the reference VREF; ri represents the inductor current sampling resistance of each phase; ILOAD represents the applied load to the system.
In this circuit, when the main Phase loop is designed to be in an Adaptive on-time Control mode (i.e., adaptive Off-time Control in fig. 1), the auxiliary Phase loop can achieve uniform distribution of power level energy by means of sequential Phase Delay (Phase Delay Control) Control. Taking a multi-phase control system with a main phase loop designed as a self-adaptive turn-off time control mode as an example, the first sub-phase turns on an upper power tube by taking a Pulse rising edge of a main phase PWM (Pulse Width Modulation) as a self loop, turns off a clock signal of a lower power tube, and compares and judges whether a self inductance current peak value reaches an error amplification signal of system output voltage feedback and an output voltage reference. And if the peak value of the inductive current in the first subphase reaches the index, switching the state of the tube to turn off the upper power tube and turn on the lower power tube so as to finish the loop regulation of each period. Similarly, the (i + 1) th secondary phase controls each period by the rising edge of the PWM pulse of the (i) th secondary phase and the comparison signal of the self peak current and the error output respectively to stabilize the current phase loop.
Based on the principle, all the auxiliary phases except the main phase follow the control mode of a peak current mode, and each phase loop needs to introduce a slope compensation circuit so as to avoid subharmonic oscillation when the system is applied with the duty ratio of more than 50% on the premise of keeping the energy balance of the power level.
Fig. 2 is a schematic circuit diagram of a slope compensation unit in a multi-phase control circuit in the prior art. As shown in fig. 2, in the conventional compensation ramp generating circuit of the multiphase control system, the signal PWM _ i is a pulse width modulation signal of the current main phase or the current auxiliary phase, the signal VCS _ i is an inductor current peak sampling signal of the current main phase or the current auxiliary phase, the signal VSUM _ i is a signal obtained by superimposing a compensation ramp on the current main phase or the current auxiliary phase VCS _ i, and i represents a phase sequence corresponding to the current PWM signal.
For the slope compensation unit, the signal IBIAS is a fixed bias current generated by a system bias circuit, and in each switching period of the ith phase, if the signal PWM _ i is turned from low to high, the upper power tube S1_ i is turned on, and the lower power tube S2_ i is turned off. At this time, the signal PWM _ i drives the switch tube M to turn off, the signal IBIAS charges the capacitor C, and generates the ramp voltage signal VRAMP _ i on the upper plate of the capacitor C, and inputs the ramp voltage signal VRAMP _ i to the voltage-controlled current source VCCS, where G1 is the gain of the voltage-controlled current source VCCS. The voltage-controlled current source VCCS converts the signal VRAMP _ i into a ramp current signal IRAMP _ i, so that the signal IRAMP _ i can be superimposed with the signal VCS _ i through a resistor R to generate a signal VSUM _ i.
Fig. 3 is a timing diagram of an output of a compensation control signal provided by a slope compensation unit in a multi-phase control circuit in the prior art. As shown in fig. 3, when the applied load ILOAD of the system is switched from light load to heavy load, the signal EAO overshoots according to the drop of the system output voltage VOUT, and under this condition, the phase loop under the high duty cycle application goes through the long-time on operation of the upper power transistor S1.
During the long-time rising of the signal VCSi following the inductor current ILi, the ramp signal VRAMP _ i superimposed thereon is distorted by the voltage margin limitation of the module circuit power supply voltage VCC, so that the slope of the signal VSUM _ i is lower than the sum of the slopes of the signal VCSi and the signal VRAMP _ i. As can be seen from fig. 3, the slopes of the signal VSUM _ i and the signal VSUM _ i +1 during EAO overshoot are difficult to maintain in agreement due to the distortion of the signal VRAMP _ i. When the signal VSUM _ i reaches the signal EAO, so that the upper power tube S1_ i is turned off, and the lower power tube S2_ i is turned on, the signal VSUM _ i +1 is still in a rising process, and the signal VSUM _ i +1 needs to wait for the time when the signal VSUM _ i finishes the falling process at the rising start of the next period, that is, the fixed delay of the time when the signal VSUM _ i reaches the valley value. During this adjustment, the signal VCS _ i +1 is vertically offset from VCS _ i, i.e., the inductor current is represented by Ili and ILi +1, which exhibit different dc levels, and the dc levels respectively reach steady states as the loop adjustment proceeds.
In fig. 3, since the signal VSUM _ i +1 misses a valley delay of the signal VSUM _ i +1 during each rising of the switching period, the switching period of the signal PWM _ i +1 is maintained twice as long as the switching period of the signal PWM _ i. Therefore, the conventional ramp generating circuit applied to the multiphase control system is very easy to cause more than one "stable" state when the system has transient response, and further causes the stability of the whole system to lose control.
In other words, in the multiphase control circuit, if the system is in an unstable regulation state, such as when a load transient response occurs, even if the rising slope of the current is kept constant, the slope of the electrical sampling signal of the inductor after slope compensation is still easy to lose control. When the slopes of two adjacent phases are charged and saturated for a long time and are limited by the redundancy of the power supply voltage of the module, the compensation effect is deviated from the designed value after the slopes are superposed on respective inductive current sampling signals, the native regulation mode of a loop is disturbed, and the stability of the system is adversely affected. Therefore, the invention provides an adaptive slope compensation technology of a multiphase control circuit.
Fig. 4 is a schematic structural diagram of an adaptive slope compensation circuit of a multi-phase control circuit according to the present invention. As shown in fig. 4, an adaptive slope compensation method for a multi-phase control circuit includes the following steps: step 1, setting a slope compensation time limit of a slope compensation unit in the multi-phase control circuit based on the power supply voltage of the multi-phase control circuit, the load limit of an inductive current sampling signal, the conduction slope of an upper power tube and the conduction slope of the slope compensation unit; and 2, realizing feedback control on the multi-phase control circuit by adopting a slope compensation time limit and a pulse width modulation signal together.
It can be understood that, in order to fully ensure that each phase control signal after compensation can not exceed the limit of instantaneous energy provided by the power supply voltage, the method of the invention firstly designs a slope compensation time limit. In other words, the length of time for the slope compensation unit to perform the slope compensation is limited in order to make the voltage rise amplitude of a single phase during the actual operation of the circuit coincide with the sum of the voltage rise amplitude generated by the upper power tube and the voltage rise amplitude generated by the slope compensation unit at the time of design. After the time length is limited, the problem that the slope compensation can output continuously theoretically does not exist, but the actual slope of the feedback voltage in the circuit cannot reach the preset index due to the limitation of the power supply voltage.
It should be noted that the conduction slope of the upper power transistor and the conduction slope of the slope compensation unit are circuit design indexes defined in the present invention, and are actually used to represent the speed of increasing the magnitude of the peak inductor current to the voltage of the inductor current sampling signal VCS and the speed of increasing the magnitude of the voltage VSUM by the slope compensation unit, respectively. Since the rising speed of the two voltages will determine the time for the signal to reach the EAO and realize the inversion of the upper and lower power tube states, the present invention will be named as the on slope. The adjustment of the index and the parameters for determining the index value will be specifically defined and explained below.
In addition, the load limit of the inductor current sampling signal may be determined according to the size of a load connected to a subsequent stage of the circuit, and when the load is fixed, the maximum value of VCS generated by the maximum load current that can be realized by the load. Since it affects the initial value of the VCS voltage at which the sawtooth-like ripple is realized, the same effect is also present for the value range of the on-slope.
In a preferred embodiment of the method of the invention,
wherein T is a slope compensation time limit, k S1_i The conduction slope of the upper power tube in the ith phase is determined by the inductance L in the ith phase i Sampling resistor R i Determination of k ramp_i For the conduction slope of the slope compensation unit in the ith phase, the current I of the current source is biased by the current in the ith phase bias Capacitance value C of compensation capacitor i Determination of V CS_load_max Sampling thresholds for inductor current, i.e. currently applied loadVCS DC value, V, at which ILOAD reaches a maximum dd Is the supply voltage of a multiphase control circuit, V dsat To maintain the saturated drain-source voltage of the charging current source in a saturated state.
It can be understood that, in this circuit, when no slope compensation is generated, if the upper power tube is in the on state and the lower power tube is in the off state, the inductor current sampling voltage in the phase loop gradually increases with the change of the inductor current, and assumes a state of increasing with a fixed slope, as a function of the inductor current in the current phase. In this case, this slope is referred to as the conduction slope of the upper power transistor in the present invention.
In addition, when the slope compensation occurs, the current IRAMP _ i generated by the slope compensation unit also causes a gradual rise in voltage, and the rise rate of the voltage per unit time caused by the slope compensation unit alone is referred to as the on slope of the slope compensation unit. Both slopes may be calculated from parameters of the relevant components in the circuit.
Therefore, after the two slope indexes are obtained, the maximum time of the slope compensation unit in a single compensation process can be limited according to the magnitude of the power supply voltage, so that the voltage cannot be increased to exceed the power supply voltage infinitely.
In addition, the charging current source is a current source for charging the capacitor in the slope compensation delay unit, and in order to maintain the saturation state of the corresponding MOS transistor in the current source, a source-drain voltage of the MOS transistor needs to be provided. It typically takes a value of 200 to 300mV.
Preferably, the slope compensation is limited to the inverse of the switching frequency of the multiphase control circuit when the upper and lower power tubes are in a steady state.
The delay duration of the delay unit DLY _ RAMP _ CLR mentioned below may determine the duration from the beginning of charging to the clearing of the signal VRAMP, and the duration may be adaptively adjusted according to the switching frequency of the current system. For example, when the steady-state switching frequency of the system is set to FSW, the delay time will be calculated as K × 1/FSW, where K is a pre-designed fixed scaling factor, which may be a positive integer. In an embodiment of the present invention, the value of K is 1.
The invention relates to a self-adaptive slope compensation circuit of a multiphase control circuit, which comprises a slope compensation delay unit, an AND gate, a NOT gate, a switch tube, a compensation capacitor, a bias current source, a voltage-controlled current source, a resistor and a superposition circuit; the first input end of the slope compensation delay unit is connected with the pulse width modulation signal of the ith phase in the multi-phase control circuit, the second input end of the slope compensation delay unit is connected with the clock signal, and the output end of the slope compensation delay unit is connected with the second input end of the AND gate; the first input end of the AND gate is connected with the pulse width modulation signal of the ith phase in the multiphase control circuit, and the input end of the NAND gate at the output end is connected; the input end of the NOT gate is connected with the grid electrode of the switch tube, the source drain electrode of the switch tube is connected in parallel with two ends of the compensation capacitor, one end of the compensation capacitor is connected with power voltage through a bias current source, and the other end of the compensation capacitor is grounded; the connection point of the bias current source and the compensation capacitor is connected to the positive phase input end of the voltage-controlled current source, the negative phase input end of the voltage-controlled current source is grounded, and the output end of the voltage-controlled current source is connected to the first input end of the superposition circuit after passing through the resistor; the second input end of the superposition circuit is connected to the inductive current peak value sampling signal VCS _ i of the ith phase, and the output end of the superposition circuit generates a feedback control signal of the ith phase.
FIG. 5 is a timing diagram of the output of the compensation control signal provided by the adaptive slope compensation circuit of the multi-phase control circuit according to the present invention. As shown in fig. 5, in this circuit, the single compensation time due to the slope compensation circuit is limited to a fixed time.
In the conventional slope compensation circuit, for the ith phase loop of the multiphase control system, the signal VRAMP _ i superimposed on the signal VSC _ i is cleared only when the signal PWM _ i is low, and the adaptive slope compensation circuit makes the signal VRAMP _ i perform the superimposition compensation function only in a set time, and the slope of the compensated signal VSUM _ i is controllable in the time and is equal to the sum of the slopes of the signal VCSi and the signal VRAMP _ i. This avoids the problem that when the current phase is in the long-time on-off operation state, for example, when a load transient response occurs, the slope of the signal VSUM _ i is out of control due to the signal VRAMP _ i being charged to be distorted for a long time, so that the stability of the whole system is damaged.
Preferably, the ramp signal VRAMP _ i is continuously charged for only the duration of one steady-state period since PWM _ i is ramped up, superimposed on the signal VCS _ i. In the working period that the current phase loop is in the state of opening the upper power tube S1_ i for a long time, the signals VSUM _ i and VSUM _ i +1 return to the signals VCS _ i and VCS _ i +1 respectively after the time of a steady-state period is reached, namely, the same rising slope is kept until the lower power tube S2_ i is opened after the signals EAO are respectively reached.
In the subsequent voltage stabilization process, because the signal VRAMP is not superposed infinitely along with the on-time of the power tube S1_ i, even if the signal VCS _ i +1 deviates from the signal VCS _ i in the transient response process, the loop can be adjusted cycle by cycle, so that the two signals enter the same stable state.
When the loop of the multi-phase control system is adjusted to a stable state, because the opening time of the upper power tube S1 must not exceed a switching cycle time, the signal VCS of each phase keeps the same superposition slope at the time when the signal VCS rises periodically in each switch and reaches the signal EAO, thereby ensuring the stability of the whole system, i.e., all phases are in the same stable state.
Compared with the prior art, the self-adaptive slope compensation method and the self-adaptive slope compensation circuit of the multiphase control circuit have the advantages that the maximum compensation time of slope compensation in each period can be adjusted, the control signal difference in adjacent phases in the circuit is prevented from being overlarge, and therefore the stability of the whole system is ensured.
Finally, it should be noted that the above embodiments are only used for illustrating the technical solutions of the present invention and not for limiting the same, and although the present invention is described in detail with reference to the above embodiments, those of ordinary skill in the art should understand that: modifications and equivalents may be made to the embodiments of the invention without departing from the spirit and scope of the invention, which is to be covered by the claims.
Claims (4)
1. A method for adaptive slope compensation for a multi-phase control circuit, the method comprising the steps of:
step 1, setting a slope compensation time limit of a slope compensation unit in the multi-phase control circuit based on a power supply voltage of the multi-phase control circuit, load limitation of an inductive current sampling signal, a conduction slope of an upper power tube and a conduction slope of the slope compensation unit;
and 2, realizing feedback control on the multi-phase control circuit by adopting the slope compensation time limit and the pulse width modulation signal together.
2. The adaptive slope compensation method of a multiphase control circuit as recited in claim 1, wherein:
wherein T is the slope compensation time limit,
k S1_i the conduction slope of the upper power tube in the ith phase is determined by the inductance value L in the ith phase i And a sampling resistor R i It is determined that,
k ramp_i for the conduction slope of the slope compensation unit in the ith phase, the current I of the current source is biased in the ith phase bias Capacitance value C of compensation capacitor i It is determined that,
V CS_load_max the maximum direct current value of the inductor current sampling signal is determined by the maximum value of the current external load ILOAD,
V dd is the supply voltage of the multi-phase control circuit,
V dsdt to maintain the saturated drain-source voltage of the charging current source in a saturated state.
3. The adaptive slope compensation method of a multiphase control circuit as recited in claim 2, wherein:
the slope compensation time limit is integral multiple of the switching frequency of the upper power tube and the lower power tube in the multi-phase control circuit.
4. An adaptive slope compensation circuit for a multi-phase control circuit, comprising:
the circuit comprises a slope compensation delay unit, an AND gate, a NOT gate, a switch tube, a compensation capacitor, a bias current source, a voltage-controlled current source, a resistor and a superposition circuit; wherein the content of the first and second substances,
the first input end of the slope compensation delay unit is connected with the pulse width modulation signal of the ith phase in the multi-phase control circuit, the second input end of the slope compensation delay unit is connected with the clock signal, and the output end of the slope compensation delay unit is connected with the second input end of the AND gate;
the first input end of the AND gate is connected with the pulse width modulation signal of the ith phase in the multi-phase control circuit, and the output end of the AND gate is connected with the input end of the NOT gate;
the input end of the NOT gate is connected with the grid electrode of the switch tube, the source and drain electrodes of the switch tube are connected in parallel with two ends of a compensation capacitor, one end of the compensation capacitor is connected with power voltage through the bias current source, and the other end of the compensation capacitor is grounded;
the connection point of the bias current source and the compensation capacitor is connected to the positive phase input end of the voltage-controlled current source, the negative phase input end of the voltage-controlled current source is grounded, and the output end of the voltage-controlled current source is connected to the first input end of the superposition circuit after passing through the resistor;
and a second input end of the superposition circuit is connected to an inductive current peak value sampling signal VCS _ i of the ith phase, and an output end of the superposition circuit generates a feedback control signal of the ith phase.
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